Supreme Court nominee Sandra D. O'Connor, testifying at her second day of confirmation hearings, said yesterday she was personally opposed to busing and in favor of the death penalty.

She also expressed doubts, based on her own experiences as a trial judge, about the hotly debated exclusionary rule, which judges use to throw out evidence illegally seized by police.

The Supreme Court is expected to confront all three controversial issues during O'Connor's life term. They are also traditional targets of Reagan conservatives, and her statements yesterday seemed certain to reinforce her own conservative credentials. These have been questioned by leaders of the New Right, though she stressed that her personal views would play no role in the resolution of cases before the court.

The first woman nominee thus concluded her testimony without mishap. In fact, though her lack of federal court experience has been criticized, many senators seemed dazzled by her command of federal law as case citations and statistics rolled easily off her tongue. At one point, she even corrected one committee member's description of a recent Supreme Court ruling.

Several Senate Judiciary Committee members did criticize her unwillingness to express opinions on specific cases, especially abortion rulings, and one, Sen. John P. East (R-N.C.), suggested that she was selectively avoiding comment in order to avoid controversy.

Her handling of that criticism typified her performance. Sen. Charles E. Grassley (R-Iowa), an anti-abortion conservative, at one point challenged her claim that it was improper to comment on cases that might come before the court. O'Connor responded with a five-minute recitation, complete with chapter-and-verse references to federal law and detailed descriptions of similar circumspection by previous court nominees.

By the time O'Connor was finishing her testimony late yesterday, senators who had come prepared with lists of difficult questions for her were yielding their time and a once-packed hearing room was half empty.

Expressing her "personal views" on busing, O'Connor recalled that as an Arizona state senator, she had supported a resolution calling for an end to federally imposed busing orders. She said that resolution is "illustrative" of her current views.

She said she rode 75 miles on a school bus as a child living in rural Arizona and had to leave home before sunup and return in darkness. "The transportation of students over long distances can be a very disruptive part of any child's educational program," she told the Judiciary Committee.

Busing, she said, "isn't a system that is often very beneficial to the child."

Her views on criminal justice also seemed to conform with the increasingly conservative thrust of the current Supreme Court. She said she had applied the death penalty as a judge and voted for it as a legislator "and I felt it was an appropriate vote then and have not changed my mind."

O'Connor also described her experiences as a trial judge with the exclusionary rule. Designed to deter police misconduct, conservatives argue that it lets criminals go free on technicalities.

It "has proven to be . . . difficult in terms of the administration of justice," O'Connor said. "There are times when perfectly relevant evidence, sometimes the only evidence in a case, has been excluded by application of the rule."

She said the rule--most often used in drug cases--"may have" contributed to an increase in the crime rate, "possibly in drug enforcement."

She said she believed it was appropriate when police had used force or trickery to obtain evidence. But she indicated she would be receptive to a modification of the sort recommended by an administration task force on crime: an exception from the exclusionary rule when police were unaware they were violating the Constitution in a search.

O'Connor also suggested that she was personally sympathetic to another task force idea: changes in the law to allow some sort of preventive detention for criminal suspects who have not yet been tried.

Her personal view, she said, was that some considerations of dangerousness--prior convictions for crimes when on bail, for example--"possibly merit consideration in the determination of bail."