Montgomery County Executive Charles W. Gilchrist, expressing confidence that he has weathered a long-running controversy over the county liquor department and has the strong support of his fellow Democrats, said yesterday he will run for reelection.

Gilchrist, whose handling of the liquor controversy as it unfolded over the past 19 months often was criticized, said it now would be ludicrous for anyone to try to beat him on that issue in next year's election.

"I don't think it can be sustained as a political issue," Gilchrist said in an interview yesterday. "People want to know 'Are you helping us?' and I'm going to emphasize my record. We've cut back on county employment without disrupting services, ended the sewer moratorium and the county has 5,000 permits for new construction."

The liquor controversy began in the spring of 1980 and centered around allegations of conflict of interest and mismanagement in the county-run department of liquor control. Since then other issues, including a $2,000 loan to a Gilchrist aide and alleged favoritism in the selection of the department's deputy director, also have developed, often putting Gilchrist on the defensive.

A series of state, independent and county investigations turned up nothing illegal about the management of the department, but some Democrats privately feel the controversy could have been handled more efficiently and fear that lingering public perceptions could alienate voters in 1982.

Gilchrist dismisses such speculation as hindsight, says that the liquor issue could not have been quashed quickly, and that voters will be more concerned about what he has done to improve the quality of life in the county over the past three years.

It was only 15 months ago, in August 1980, when Gilchrist, swamped by liquor department allegations, threw a pen across the room at a press conference and said "It's days like this I just want to quit; it disgusts me."

Yesterday, hours before he was due to be honored on his 45th birthday at a Capitol Hill party sponsored by Sen. Paul Sarbanes and Democratic Congressmen Michael Barnes and Steny Hoyer, Gilchrist looked relaxed, joked about the realities of Montgomery County politics, and appeared eager to demonstrate his ability to win what he feels will be a bitter and negative campaign.

"The real question," Gilchrist said, "is are we going to be able to get away from the 'Who struck John?' feeling. I've got to do it the hard way. I'm not good at negative campaigning."

He added that he will emphasize face-to-face campaigning at Metro stops and shopping centers. Ed Rovner, an aide, said later that Gilchrist raised $30,000 at a fund-raiser earlier this year and has started conducting a series of Sunday meetings at his home for local Democrats.

Gilchrist, whose formal declaration of candidacy for reelection is not expected until the spring, dismissed speculation that he is interested in or has been contacted as a possible candidate for liuetenant governor. "I've given it very little serious thought. There has been no serious discussion of my doing anything but seeking reelection," Gilchrist said.

Gilchrist said that he is not ignoring the possibility that he will be challenged in a primary. Most political obsevers in the county feel his only real competition for the Democratic nomination would come from Councilman David Scull, the son of two prominent Montgomery politicians.

For the record, Scull has said nothing more than that he has not planned to be a candidate, but reserves the right to run "if it appears that Gilchrist couldn't win" a general election.

Gilchrist also discounted the effect the Reagan administration might have on county elections, citing the recent governor races in Virginia and New Jersey that showed that "either Reagan isn't that popular or his popularity doesn't define local elections." Local elections generally are won on local issues.

Gilchrist could joke about the accusations that has been leveled against him -- everything from the charge by local veterinarians that he was "on the take" in pushing for a low cost spaying and neutering clinic, to the time when he said he dumped a load of old Sarbanes campaign literature in the county landfill and found reporters at his door asking what secret documents he had disposed of.

There was nontheless a hint of bitterness in Gilchrist's tone as he expressed his disappointment in both the county council and personnel board in taking what he considered to be a long time to complete their investigations of liquor-related issues.

"There are people who have done everything they could to hype and extend" the liquor controversy, Gilchrist said. "Some people in the Democratic party are just not in the habit of coming forth to defend a person when he needs it . . . I put myself in the hands of others."

On other issues, Gilchrist said he believes the county faces a problem in the increase of racially or religiously motivated acts of violence, but said he does not feel the county is becoming a "bastion of hatred. It's a problem that has always been with us," he said, adding that figures showing dramatic increases in racial incidents are partially the result of the county's emphasis on encouraging people to report them.