Ten years after Virginia first allowed liquor by the drink, the state has decided to loosen restrictions on advertising for the places that sell it.

In the first major revision of its regulations since 1972, the Virginia Alcoholic Beverage Control Board announced yesterday it will now allow such establishments to advertise with a one-foot square symbol of a martini glass. A small circle representing an olive in the bottom of the glass also will be permitted.

The ABC board, most recently in the news for its refusal to allow the sale of Billy Beer because it carries an endorsement by President Carter's brother, also said it will allow breweries - but not liquor distilleries or wholesalers - to sponsor sports events.

Anheuser-Busch, which has a brewery near Williamsburg, was a prime backer of the proposal. An Anheuser-Busch spokesman told the ABC that the brewer wanted to sponsor a golf tournament at its Kingsmill course.

The new regulations will allow sponsors to give participants gifts with beer brand names on them, but uniforms used in the events, trophies and advertising may carry only the company name.

Wineries, an increasingly important business in Northern Virginia, will be able to place two signs, three-by-five feet, within five miles of the winery. The signs may give the winery's name and the names of products it makes and sells.

Several of the new ABC regulations stem from action by the General Assembly. On July 1, customers will be allowed for the first time to drink standing up in Virginia. The ABC board adopted a rule that a bar may be of unlimited length, as long as its capacity at 2.5 feet per person is no greater than a third of the total table capacity.

The assembly also barred flip-top cans after Jan. 1, 1979, and the ABC board said that such beer cans could not be shipped into the state after Oct. 1 or delivered to retailers after Dec. 1.

The board increased its power to restrict ads it considers "blatant, obtrusive or (which) encourage intemperance." It did not ease the prohibition against label endorsements by "any prominent, living person," under which Billy Beer is banned.