About 400 Boston University professors and students walked out of class yesterday to protest the school's awarding an honorary degree to the controversial chief of the Zulu tribe in South Africa.

The protesters staged a rally outside the school's Law School Auditorium as President John R. Silber presented Chief Mangosuthu Garsha Buthelezi with an honorary doctor of laws in an invitation-only convocation.

Before Buthelezi delivered his acceptance speech, about 10 students stood and shouted for him to "go away," said Narenda Nadwer, managing editor of the B.U. Daily Free Press.

In his speech, Buthelezi criticized those who can see no solution to the problem of apartheid other than violence, Nadwer said. The junior added that the protest "was the most effective show of opposition he had seen in his three years at the university."

"It was a reawakening of activism with a purpose on campus," said Terrence Morrow, president of the Afro-American Student Association "umoja," a B.U. pro-divestment group.

"You can kind of get a feel for what Buthelezi is about by the people who support him--Silber, [South African President P.W.] Botha, President Reagan," Morrow said.

University officials said they were not surprised by the protest and stood by their decision to honor Buthelezi.

"We think most people worth honoring would be controversial," said Sam McCracken, assistant to Silber. He said that the Zulu chief is a leader who "Works within the system [of apartheid] to destroy it."

Vice President for International Projects Edwin A. Penn said that Buthelezi was worthy of the school's honor because his ideas are consistent with the university's policy on divestment and sanctions against South Africa.

In addition to heading the six-million member Zulu tribe, Buthelezi is the president of Inkatha, said to be South Africa's largest Black political party. He opposes divestment and sanction against the South African government and thinks that the Blacks can use peaceful means to obtain a proportioning of power by all races in his native land.

"He more than any other Black political leader, through his political action, has contributed to the destruction of apartheid, while at the same time he speaks strongly against sanctions and disinvestment and against violence of all kinds in South Africa," said Associate Dean Ronald Goldman.