The Arlington School Board voted last night to change a controversial 1971 busing desegregation plan by allowing the youngest black pupils affected by it to attend schools closer to their homes.

The board has come under attack recently from blacks who argue that their children are bearing the burden of desegregation as a result of the 12-year-old plan that dictates that they must be bused to improve the racial balance at far-distant county elementary schools.

Last night's unanimous action came after initial opposition from two board members who questioned whether it violated the terms of the original court-approved plan and expressed concern that it would upset the racial balance of some schools.

Board Vice Chairman Simone (Sim) Pace said that by "trying to do something good" the board might "wind up doing something not good . . . nor bad."

County Attorney Charles Flinn earlier this week advised the board that it would be legally proper to amend the plan but cautioned that the racial balances at some schools in North Arlington would be upset by proposals to reassign 59 black kindergarten-through-third grade pupils to the Abingdon, Barcroft and Randolph elementary schools near their homes in South Arlington. As a result of last night's vote, the pupils in question will be reassigned to those schools in the fall.

Flinn had warned that taking the black students out of the North Arlington schools they now attend would reduce in some cases the black enrollment at those schools to 4 percent.

Questioning the legality of the action last night, board member Claude Hilton, a lawyer, said he favored addressing the plight of the children--who now spend as much as 40 minutes one-way being bused to county schools far from their homes--but only "if it can be done within the confines of the plan."

Board Chairman Evelyn Reid Syphax, who is black and who proposed the changes, reacted angrily to the Pace and Hilton remarks. "I cannot believe that you feel we're going to recreate an all-white school," she said. Syphax said a checks-and-balance system already used to monitor racial and ethnic balance would prevent any concentration of white or black students.

"I think it would be insensitive not to approve the proposals tonight," she told her colleagues.

After much debate and more questions on whether approving the proposal could lead to massive busing, create scheduling problems or be legally invalid, County Attorney Flinn reaffirmed his legal opinion, saying he did not think the proposal "violates the plan."

Black leaders in the audience called for further changes in the system, which does not require busing of any other racial or ethnic group. John Robinson, director of the Martin Luther King Community Center, asked that more South Arlington students be allowed to attend nearby Drew Model School, which is 20 percent black. "We need to stop using black children as quotas," he said.

The busing decision came near the end of a lengthy meeting at which a number of redistricting proposals aimed at improving racial balance in schools were addressed.

Board members set new high school attendance boundaries that generally call for shifting some students to Yorktown High in North Arlington, the county's smallest high school. Only 42 to 50 students would be initially affected in the fall of 1984, according to operations director Henry Gardner.

The board initially asked for the high school redistricting proposals in an effort to equalize enrollments at the county's three high schools and improve racial and ethnic balances there.

Hilton and board member Michael Brunner opposed the boundary changes, saying they did not resolve the board's racial balance concerns. "We can say [the boundary plan is] a step forward" in improving racial and ethnic balance but "it really isn't," Hilton said.