The Senate voted yesterday after seven days of debate to renew provisions of the 1965 Voting Rights Act for 25 years, passing the most controversial civil rights legislation of the 97th Congress.

The House, which approved a comparable measure last year, is expected to gloss over minor differences between the two chambers' versions so the bill can be on President Reagan's desk early next week. The final Senate vote was 85 to 8.

The new act guarantees equal access to the voting booth and the political process and extends for the third time a law believed to have helped several million blacks and other minorities register to vote.

It in effect overturns a 1980 Supreme Court ruling requiring complainants to prove that local officials intentionally produced any existing discrimination. It also maintains federal controls on voting rules in areas with records of discrimination, while easing the way for localities to bail out from under the law.

The vote to extend was the product of a strong 1960s-style grass-roots campaign over the last 15 months by civil rights groups working with a coalition of Democratic and moderate Republican senators.

"This is another watershed in civil rights," said Sen. Robert J. Dole (R-Kan.), who joined Sens. Charles McC. Mathias Jr. (R-Md.) and Edward M. Kennedy (D-Mass.) in authoring the final compromise. "It will stand the test of time and ease the fears" of its opponents, Dole said.

Reagan, who opposed the measure in its original form last year but embraced it in the face of its overwhelming support, said the Senate vote was "a statesmanlike decision." He has said he will sign the bill into law.

Although the White House mounted no major lobbying effort for extension, "the president's public position was very helpful," Mathias said.

Sen. Jesse Helms (R-N.C.), leader of conservative opposition in a filibuster that delayed consideration of the bill for five days, predicted that the vote "may well rival the Panama Canal giveaway in its political implications four or five years down the line" for its supporters.

Helms described the bill as "purely punitive" against the 22 states with jurisdictions where the bill is in effect.

After voting, 97 to 0, to silence Helms and take up the measure Thursday, the Senate considered 22 amendments in less than 24 hours, rejecting all major changes.

In return, Helms won agreement from Majority Leader Howard H. Baker Jr. (R-Tenn.) to debate Helms' proposed constitutional amendments to ban abortion and restore prayer in public schools when the Senate takes up extension of the national debt ceiling next month.

"We paid no price at all," Mathias said, but Laura Murphy of the American Civil Liberties Union office here was not as certain of that. "I hope the rights of women weren't traded off for the votes of minorities," she said.

The Voting Rights Act will continue to require electoral districts with poor minority voting histories to submit all proposed changes in voting procedures to the Justice Department. But, for the first time, a town or county able to demonstrate good behavior for 10 years can get free of that restriction by appealing to the U.S. District Court here, even if its state's actions remain covered.

The bill also requires federal judges to consider the totality of a situation in order to find that racial discrimination has resulted. Relevant factors include the affected area's history, minority representation in elected positions, voting patterns and access to education, jobs, the political process and health care facilities.

Opponents had charged that such a standard would lead to racial quotas and proportional representation in every elected body and that courts should be required to find that officials had intended to discriminate.

The Leadership Conference on Civil Rights, a coalition of 160 groups including the Roman Catholic Church and the American Bar Association, argued that such a standard was impossible and would often require courts to evaluate motives of local officials long since dead.

Voting against extension were Republicans Steve Symms and James A. McClure of Idaho, Gordon J. Humphrey (N.H.), Helms and John C. East (N.C.), S.I. Hayakawa (Calif.), Jeremiah Denton (Ala.) and Independent Harry F. Byrd Jr. (Va.).