With a mixture of homespun Virginia humor, East Coast business savvy, a New York public relations firm and an advertising agency, Fairfax County brought its story to the world today, or at least another part of it.

The story of Fairfax County-that it is a good place to live and work-was preached with zeal here today to national and international business publication reporters in the county's latest push to entice more and different business to its undeveloped soil through "punchy" publicity.

"We wanted to do something dramatic," said Ted M. Levine, of Development Counsellors Intl.l Ltd., the public relations firm handling Fairfax County's account. Fairfax is one of the few countries to bring its message to New York, leaving said, because "in other places there isn't as strong a story. The story is basically the growth of the county, the growth of trade associations in the country."

"Fairfax County is one of the half dozen fastest growing counties in the United States," Levine continued, "and only one of six with a AAA bond rating by both bond services."

"What other jurisdictions are doing is dull" as far as advertising themselves, said Earle C. Williams, chairman of the Fairfax County Economic Development Authority which sponsored the media event. "A number of us were in the private sector and dealt with advertising and we knew (dull advertising) wasn't it. You need a punchy program." And to the surprise of the 17 state and county officials, including Lt. Gov. Charles S. Robb, who attended the cocktail party and luncheon in a posh Manhattan hotel, more than twice the number of reporters expected showed up.

Many of them wanted to know what and where Fairfax County was, Williams, said. So between Bloody Marys and beefsteak the county officials delivered the county's story to about 50 reporters. The luncheon cost the county about $1,300 and accommodations for the nine county officials overnight in the hotel amounted to about $2,000, another county official estimated.

"Nevertheless news stories are cheaper than advertising," County Board Chairman John F. Herrity quipped to a reporter.

The county Economic Development Authority doubled $800,00 budget on advertising, Williams said. It has included full page ads in national magazines and the Wall Street Journal, placement of response cards in advertising, many of which were mailed back by "a lot of kids and librarians," Williams said.

Prince Georges County and the District have recently stepped up campaigns to attract business, but not on the scale of Fairfax.

The main selling point in the program today was the opening of about 8,000 acres of land along the new Dulles International Corridor that is expected to bring in more than $1 billion in large-scale commercial and indutrial development. Robb described it as "what is certainly one of the last real development frontiers in the famous Northeastern megalopolis that stretches all the way from Boston to Norfolk."

The development prospect stems from recent authorization by the Virginia legislature of a $57 million access toll road parallel to the existing expressway which exists only to the airport.

As a testimonial to its desirability, the county brought along a recent convert, Fred Lienard, whose Belgium development firm, Gest Invest, is planning to build an industrial park with 1.5 million square feet of office space on 140 acres of the new Dulles access land. After checking Richmond, New York, Boston and Toronto, Lenard said he chose Fairfax County.

"It's only 31/2 hours from London," via the Concorde, Lienard said, and it is close to Washington, which is economically stable.

If approved next month by the county planning commission and in July by the board of supervisors, Liehard said he will start promoting the industrial park in Europe. To sell the park abroad I will speak of Washingtoin, definitely . . . Afterwards I would speak of Fairfax County and the potential it presents," Lienhard said after his brief testimonial.

Gest Invest, which has assets of about $5 million and has constructed 1.5 million square feet of housing and commercial development in the past four years, recently completed the development of a new town outside Brussels. A drawing point for the county was the opening up of the access area, Lienhard said.

The county is not only trying to imprint in the minds of national and international businesses that Fairfax is desirable, but it is trying to erase an image as a no-growth community which is hostile to business. That reputation was earned during the early 1970s by county supervisors who felt the county was growing too rapidly and would not be able to handle such expansion.

"In 1972 real estate, commercial and industry taxes dropped as a percent of the total tax load," Williams said. "That's not a good way to run a government jurisdiction." The county now has a goal of having its commercial business tax base up to 25 percent by the year 2025. It is now about 13 percent, William said.

Last year the county issued $213,200,000 in commercial building permits, almost double the $110 million in 1974. Last year's permit figures represented 38 percent of all such construction registered in the Washington metropolitan area, Williams said.

Some of the more recent relocations or expansions in Fairfax were made by Mobil Oil, American Telephone and Telegraph, Sperry Univac Division and Merrill Lynch. Also the number of trade associations headquartered in the county increased from two in 1970 to 125 this year. CAPTION: Picture, Virginia Lt. Gov. Robb, left, Fairfax Chairman Herrity and Economic Development Chairman Williams. AP