Pope John Paul II yesterday announced the retirement of Philadelphia Cardinal John Krol and named as his successor Bishop Anthony J. Bevilacqua of Pittsburgh.

Bevilacqua, a strict constructionist of church law, is expected to continue Krol's conservative policies.

Krol's resignation, which was offered two years ago when he reached the mandatory retirement age of 75, marks the end of a 51-year career that helped transform the American Catholic church from an institution of immigrants to a church influential in the mainstream of American life.

Bevilacqua's appointment as archbishop is expected to be viewed as a setback by those who want a wider role for women in the church. In 1985, two years after he became bishop of Pittsburgh, he set off widespread protests when he directed priests not to admit women to the Holy Week rite of foot-washing, reversing a longstanding practice in the diocese.

Bevilacqua, 64, argued that none of the 12 apostles whose feet Jesus washed were women. That washing was part of the historical precedent for the ritual.

In widely publicized protests, some women's groups and priests staged alternative hand-washing rites. A year later, the Committee on the Liturgy of the National Conference of Catholic Bishops, in response to Bevilacqua's request for clarification, ruled that women were to be included in the ritual.

In 1983, as a special Vatican emissary, Bevilacqua ruled that a Michigan nun who directed the state's social services could not continue as a Sister of Mercy because the agency she administered funded abortions.

The eighth of 11 children of Italian immigrant parents, Bevilacqua was named auxiliary bishop of Brooklyn, N.Y., his home diocese, in 1980. Already proficient in church law, he attended St. John's University at night while he was auxiliary bishop to earn a secular law degree in order to aid the thousands of refugees and immigrants who turned to churches for help.

When he takes over Feb. 11, Bevilacqua's conservative leadership is expected to make few waves in the 1.3 million-member archdiocese, which Krol's firm hand has kept relatively free of most of the changes called for two decades ago by the Second Vatican Council.

Philadelphia is "like a time warp . . . almost like a museum of what the church used to be," said a prominent lay Catholic who asked not to be identified.

The son of a Polish-born machinist, Krol became friends with Pope John Paul II when the pope was still a bishop in Poland. Those ethnic ties, plus Krol's unquestioned leadership abilities, gained him a place of influence in Vatican affairs. He is leading efforts to reduce the rapidly growing debt of the world church.

Krol accepted invitations to preach at private church services in the Nixon White House, and during the 1972 election campaign, provided President Richard M. Nixon with a platform when the National Catholic Education Association met in Philadelphia.

As the second president of the National Conference of Catholic Bishops, Krol, an outspoken anti-communist, fended off efforts by some of his colleagues to put the bishops on record in opposition to the Vietnam war.

But in 1979, he testified before Congress against the use of nuclear weapons and gave strong support to the bishops' 1983 pastoral letter condemning nuclear warfare.

There is speculation that Bishop Donald Wuerl may fill the Pittsburgh vacancy. Wuerl has been without a see since his removal earlier this year from the archdiocese of Seattle.

The Vatican sent Wuerl to Seattle in 1986 as part of the disciplining of Archbishop Raymond G. Hunthausen, who was accused of failing to enforce church doctrine in such areas as divorce, homosexuality and married priests. Massive protests forced the Vatican to withdraw Wuerl.