A lawyer hired by the Montgomery County Council to investigate the county's liquor distribution operation reported yesterday he has found no evidence of illegality, favoritism or improper influence.

County Executive Charles W. Gilchrist, who has been dogged for more than 1 1/2 years by allegations of improprieties in the county Department of Liquor Control, hailed the report by Robert P. Trout as vindication.

"I am pleased that the Trout report concluded that my administration was innocent of any improper or illegal conduct," Gilchrist said in a statement, adding: "I hope that we can now devote our attention to the real problems facing the people of this county."

Trout, a Washington lawyer whose report fills 116 pages with 250 more pages of exhibits appended, declared that his investigation puts to rest allegations of favoritism and charges that deals were made in exchange for political contributions.

But Trout told a reporter: "It is my overall impression that the Department of Liquor Control is neither as sick as its severest critics profess, nor as healthy as its most ardent supporters suggest."

He also said the county's Code of Ethics is both unclear and "inartful" and should be amended if the County Council wishes to prohibit conduct that raises the appearance of impropriety. He also recommended that the selection of alcoholic beverages for sale in the county should be made by a committee rather than by individuals to avoid the appearance of favoritism.

The controversy over the agency that has a monopoly of the distribution of all alcoholic beverages in the county has come to be called "Liquorgate" and has generated a half-dozen investigations by such bodies as the local chamber of commerce and the board that watches over the county's merit personnel system.

Still another investigation is under way. The Merit System Protection Board recently was given $50,000 by the County Council to study certain allegations of hiring violations based on the board's earlier inquiries into the liquor controversy.

In his report, Trout avoided dealing with issues that are the subject of the merit agency probe. He also avoided judgments of the wisdom of business dealings by the liquor department.

Leonard Colodny, a former liquor wholesaler who has become one of Gilchrist's political antagonists, said yesterday that "what Trout was saying was that Gilchrist didn't do anything illegal according to statute. He didn't break the law."

He added that reports to date demonstrate "a pattern of activity that constitutes political crime. All the evidence is in. Now it will be before the voters of Montgomery County to judge whether they want Mr. Gilchrist to run their government."

Colodny was once hired by Gilchrist to look into the liquor department and proceeded to raise issues of mismanagement and charge that Gilchrist was making decisions that favored wine and cheese businesses to the detriment of the department.

Trout found in his investigation that:

* There was "no evidence establishing the existence of favoritism by the liquor agency toward any particular distiller." He also said no licensees -- businesses, such as restaurants, licensed to sell liquor by the drink -- indicated that they had been induced to purchase particular brands of spirits because of gratuities and "everyone interviewed disclaimed the existence of . . . inducements."

* Only $540 of more than $128,000 donated to Gilchrist's 1978 county executive campaign was given by beer and wine licensees and "certain other individuals who have been active in the Beer and Wine Association. . . made no contributions to Gilchrist." Further, there was "no evidence of any improper campaign activities" by persons who did contribute.

* There was nothing illegal about a $2,000 loan made in January 1980 by Charles Buscher, a former executive of Schenley Industries, to Gerard Evans, then a special assistant to Gilchrist. But Trout said Evans' acceptance of the loan "raised the justifiable impression in the public's mind that Evans may have violated a public trust . . . He should not have approached Buscher for the loan."

* The county chamber of commerce report on the liquor department was unbiased even though no beer or wine licensees were included on the committee that conducted its investigation and "there was no evidence that its recommendations were made in bad faith as a ruse to transfer the liquor business . . . to the private sector."