Like many American parents in recent years, Charles Sellier had a lot of trouble finding suitable movies for his young family. But unlike most, Sellier, a Mormon studio technician with a 10th-grade education, decided 10 years ago to take Hollywood on.

Today Charles Sellier is the first of a series of new family-filmmakers that is hitting Hollywood right where it hurts - the box office. Dressed in a plain blue leisure suit, his hair unfashionably unstyled, Sellier doesn't look the part of a movie mogul. But since he founded his Utah-based Sunn Classic Pictures in 1969, Sellier, 34, has put together one of the longest strings of money-making multi-million-dollar movies in the business.

Sunn Classic's success has come without the approval or even the acknowledgment of the traditional opinion-makers of the motion picture industry. None of the company's films has ever even been nominated for an Academy Award, nor do the powerful New York critics often bother to review Sunn Classic releases. But by producing what Sellier believes the average family wants Sunn Classic - with such pictures as "The Live and Times of Grizzly Adams" and "In Search of Noah's Ark" - has been able to fill movie houses around the country. His newest, "The Lincoln Conspiracy," is being helped along by a whopping $5-million television advertising budget.

"Look, I've done 26 feature-length films and made $15 million a film, and you don't even know who I am," complains Sellier, a native of Mississippi. "If I was in Hollywood now, I'd be Cecil B. DeMille."

Sellier believes Hollywood's failure to tailor its products for family audiences is the key to Sunn Classic's success. By its frequent use of explicit sex, violence and vulgarity. Sellier thinks mainline Hollywood has relinquished its hold on a large section of the movie-going public.

"I discovered there was a void for a particular kind of picture," he maintains. "The people are becoming more aware of what's good for them. They're becoming more uneasy with what's been coming. There's a demand for less violence and sex coming from a lot of people out there."

Many Hollywood executives dispute Sellier's claim, pointing to such movies as "The Bad News Bears" and "Star Wars" as examples of big studio interest in family films. "We're not ignoring the family market," insists Thom Mount, vice president of Universal Studios, Hollywood's largest. "We have movies like 'Heroes,' which is a simple love story. It's not 'Benjy Com Home,' but anyone in the family can come and enjoy it."

But Mount insists that the studios, with their massive facilities and star salaries and union technicians, simply cannot afford to make the strictly "G" rated fare served up by Sellier.

The language of "Bad New Bears," or the built-in violence of "Star Wars" may result in a "PG" instead of a "G" but it also results in a bigger gross.

According to mount the major studios do not make most of their money in places like Idaho or Utah, but in more metropolitan areas such as New York and Los Angeles. "The family film thing is comparable to the phenomenon of black pictures in the 60s," Mount said. "You can only make money if you do it quickly and with low overhead."

In aiming at the family film "void," Sunn Classic has shown the rest of the motion-picture industry that money can be made in family entertainment. Sellier boosts his profits by filming with non-union crews in often spectacular Utah locations and using obscure actors rather than big names.

The highly popular "The Life and Times of Grizzly Adams" is a proto-typical Sunn Classic production. Conceived at a June 1973 meeting at a Los Angeles Holidy Inn, "Grizzly" was filmed on location in Utah for $125,000 and released in November of that same year. Ignored by critics and film buffs, the movie has by now grossed $24 million, according to Sellier, and spawned a television series on NBC.

"Grizzly" proved something to Sellier. "When I got into the business everyone said you couldn't make money with a G-rated film," he recalls with a sly little smile. "But I gave them Grizzly Adams - nonviolent, non-sexual, just a guy walking around with a bear with a smile on his face, and last season on NBC we beat out the Bionic Woman in the ratings."

Sellier hopes Sunn Classic is the forebear of a new entertainment industry that will shed the show-business image immorality and general sleaziness. Himself a convert to the Mormon faith, Sellier runs his studio in Park City, 30 miles from Salt Lake, with the aid of a predominantly Mormon staff.

Down the road in Orem, Utah, another group of Mormons, the singing Osmond family, is building its own new multi-million-dollar film studio. Having won the hearts of millions of teeny-boppers for years, the Osmonds are now heading out to capture the whole family.

"I see a whole new trend in the industry moving over to where we don't have to get down low in the gutter," says Alan Osmond, 28, the oldest son of the singing family and vice president of Osmond Productions. "Maybe it's our Mormon faith, but I think something different. There's a market for good, wholesome family - we wouldn't be there if there wasn't."

Osmond says he'd like to emulate Sellier's success, but plans to spend more money on his product in order to turn out more sophisticated, professional-looking family films. "I mean something like 'Rocky' really wasn't bad family entertainment," Osmond maintains. "I saw it. It was inspiring. You know, a family film doesn't have to be a boy and his dog."

Dick Callister, the crew-cut lawyer who serves as president of Osmond Productions, says his Los Angeles-based company will try to enlist the support of PTA, religious and other family groups."We want to tell them there's a market for family films, but we're asking them to show it by going to the films," Callister said.

"This business is sick," Alan Osmond says. "You ask anybody. There's a lot of sickness. In the material they do, in the way business is conducted by the majors. We've been burned and we know."

The activity at the Great Salt Lake is not being totally ignored back in Hollywood. Walt Disney Productions, which for decades dominated the family entertainment business, is trying again to regain its premiere position.

Disney's film strategy is now centered on "Pete's Dragon," a $10-million fantasy starring Mickey Rooney and Helen Reddy. Disney executives, who concede things haven't been the same since the death of the founder, are touting "Pete's Dragon," which goes into national release this Friday, as a potential Academy Award winner.

Robert King, head of marketing for Disney Productions, believes today's movie-goers are ready for a big-time family movie. "What 'Star Wars' and 'Rocky' showed is that an upbeat escape picture can work. Anything that makes you feel good and is kind of unique and audio-visually interesting has a good chance of making money," King said. "And, if you market it right, you can make a huge amount of money."

Those at Disney aren't the only ones to notice. Last week Bill Osco, who has produced such soft-core movies as the X-rated "Alice in Wonderland" and "Flesh Gordon," announced that his next project will be a PG-rated kids-play-football film called "Peewee Pigskin." Osco told the press he only did the other films for the money, that making family films is "what I've always wanted to do."

Producer Robert Evans recently announced his newest project will be a children-oriented movie musical based on the character of Popeye the Sailor Man, starring Dustin Hoffman as the spinach-munching muscleman and Lily Tomlin as Olive Oyl. Another big producer, Sir Lew Grade, is also making a family feature, his based on "The Lone Ranger."

All this activity may turn out to be little more than a brief stirring in the trendy world of Hollywood, but men like Osmond Productions' chief Dick Callister hope it is more.

"For a long time around here all the things that have been no-no's haven't been no-no's anymore," the Mormon lawyer said. "We've made things easy by taking away the sense of conscience from the industry. It will be something if we can get it back."