The national zoo, after more than two years of controversy over how to control the overcrowded white-tailed deer population at its exotic game farm in Virginia's Blue Ridge Mountains, has found a solution: Give up.

Sometime this spring, zoo officials will remove sections of the fence around the 3,100-acre Conservation Center in Front Royal, and simply let the native deer come and go freely. Zoo officials hope many of the deer will go for good into the surrounding forest.

"It boils down to looking at a variety of solutions to the problems," said zoo spokesman Robert Hoage. "This seems to satisfy a lot of the interests."

Officials of the zoo, which is overseen by the Smithsonian Institution, had unsuccessfully tried herding the deer out of the farm for two years. In 1981, the farm was opened to deer hunters, a practice Congress stopped last fall after complaints from individuals and animal protection groups. A $650,000 plan to build 12-foot high fences and relocate the deer also was blocked by Congress in December.

The latest deer solution is expected to cost $120,000 to $140,000, says a Smithsonian spokesman, most of it to raise some interior fences to keep the native deer away from the foreign animals kept on the farm and the crops planted for them to eat.

The deer pose a threat of disease to the rare zoo animals at the preserve for recuperation and breeding. They also eat alfalfa and other crops planted for zoo animals, Hoage said.

Environmentalists, some Friends of the National Zoo and even a group of hunters lobbied Congress to block last year's deer hunt, which they criticized as a government-sponsored "slaughter."

Under the latest plan, which Smithsonian officials said yesterday apparently has the blessing of congressional committees, the 6-to-8-foot perimeter fence will be lowered to 4 feet in several remote sections of the preserve this spring.

The low fences "will be like jumping a downed tree for them," said Hoage, and will make it easier for the deer and fawns to leave the preserve, "which is overcrowded and overgrazed" with about 1,000 deer, Hoage said. The present fence can easily be jumped by grown deer, but because young deer cannot apparently jump the fence, adults also stay within the preserve.