Clarence Thomas, a conservative black lawyer who has expressed several reservations about the traditional role of the Equal Employment Opportunity Commission, was nominated yesterday by President Reagan to head the agency.

The son of a poor Georgia farmer, Thomas, 33, is a graduate of Holy Cross and Yale Law School, and is assistant secretary of education for civil rights in the Reagan administration.

He was nominated after the White House apparently gave up on winning Senate confirmation of William Bell, president of Bold Concepts Inc., a one-man Detroit employment agency that placed no clients last year.

Bell was strongly opposed by civil rights groups and senators as being unqualified to run the chief federal agency charged with enforcing laws against discrimination.

Thomas, a Republican, is a longtime supporter of Reagan and a member in good standing of the fledgling black conservative movement led by economist Thomas Sowell. He opposes using school busing and affirmative action quotas as the principal instruments for overcoming the effects of past discrimination.

Like Sowell, Thomas has indicated a feeling that he was victimized by affirmative action because whites in college and law school felt he was there only because of racial quotas. Before taking the civil rights post at the Education Department, Thomas had deliberately avoided jobs that dealt with black issues.

In an interview shortly before Reagan's inauguration, Thomas had said:

"If I ever went to work for the EEOC or did anything directly connected with blacks, my career would be irreparably ruined. The monkey would be on my back again to prove that I didn't have the job because I'm black. People meeting me for the first time would automatically dismiss my thinking as second-rate." Yesterday, Thomas said he "pretty much ate my words" when he took the Education Department post. He said he was persuaded to do so by friends who reminded him of his strongly held beliefs that the path to progress for blacks differed from approaches advocated by civil rights groups.

"Somebody's got to do it," he said. "The job's got to be done. My friends just said to me that it's put up or shut up time."

If confirmed, Thomas said he intends to approach the EEOC job with an open mind, but he made clear that he still holds conservative views in opposition to rent control, busing, affirmative action and the minimum wage.

On affirmative action, he said:

"I will state as a bottom line that I am tremendously in favor of equal opportunity, and I will not deny that we have suffered adverse effects from racial discrimination. I know what it is to be scorned and not be able to go to movies and parks and drink out of water fountains.

"But my point is that we have gotten into a position where we believe that prescribing proportional representation is a solution to the problems that we have, and I don't agree with that. To the extent that a rigid quota system is affirmative action, I disagree with that."

On busing, he said:

"I have not seen why it's got the attention it's gotten. The problem is educating our kids, not which school they go to. That is not to say they should go to all black schools or we should resegregate our schools.

"We're spending an enormous amount of energy on busing. You wind up busing a kid from Roxbury to South Boston, but what have you got? You're busing a kid from a bad school to a bad school."

Thomas attended segregated schools in Savannah, Ga., until transferring as a 10th grader to study for the priesthood at a seminary where he was the only black student and became known derisively among classmates, he said, as "the black spot on the white horse."

Thomas said he retains a searing memory of being regarded initially there as "inherently inferior," but he said that attitude spurred him to do well.

After leaving the seminary for Holy Cross, he was involved in black student protests to change grade requirements and eliminate mandatory courses in the sciences.

But, he said, he ultimately came to feel that the high number of blacks whose low grades placed them near the bottom of class rankings or led to their dismissal there had less to do with the college than with the students.

Now on Holy Cross's board of trustees, he reflected a year ago: "We have changed course requirements, we have given remedial assistance and hopefully we have created better black students. But they are still lumped at the bottom of the class."

After Yale Law School, he went to work for Sen. John C. Danforth (R-Mo.), then that state's attorney general. He later worked for the Monsanto Corp. as an attorney and then joined Danforth's Senate staff before taking the Education Department post.

Maudine Cooper, Washington representative for the National Urban League, was enthusiastic about Thomas' nomination. "He has his own notions, and they're no different from the other Reaganites," she said. But, she said she finds him bright and personable, and said, "I think he will listen."

Arnoldo Torres, executive director of the League of United Latin American Citizens, who had led civil rights groups in opposition to Bell's nomination, said he has found Thomas insensitive to Hispanic problems while in the education job.

Meanwhile, controversy continued over Reagan's nomination of B. Sam Hart, a black north Philadelphia radio evangelist, to the U.S. Commission on Civil Rights. Despite widespread calls for withdrawal of Hart's name, White House deputy press secretary Larry Speakes said yesterday, "I have heard nothing in the White House to indicate a change of mind."

Hart was recommended for the job by Sen. Strom Thurmond (R-S.C.), Rep. Trent Lott (R-Miss.) and Sen. Roger W. Jepsen (R-Iowa). A Lott spokesman said congressmen got Hart's name from Rep. Richard T. Schulze (R-Pa.), not "right-wing religious groups," as reported previously.