JACKSONVILLE, FLA., DEC. 1 -- President Reagan today combined harsh criticisms of Soviet conduct around the world with the hope that his summit discussions with Soviet leader Mikhail Gorbachev next week would lead to generations of peace.

In a speech to 8,500 high school seniors and their parents here that focused on the summit, the president said, "I want my meeting with Mr. Gorbachev to help build a true peace that will last for your lifetime, and that of your children, and of their children."

Answering questions from honor students after the speech, Reagan said that when he and Gorbachev sign the intermediate-range nuclear forces (INF) treaty next week the two superpowers "will have started down the road to the elimination of nuclear weapons."

Reagan praised Gorbachev in the question-and-answer session, saying he was "quite different than past Soviet leaders." The president said Gorbachev was the first Soviet leader ever to agree to eliminate nuclear weapons already in the Soviet arsenal and "also the first Russian leader who has never reiterated . . . that the Soviets are pledged to expansion -- a one-world communist state."

The president acknowledged to a student questioner that Gorbachev was popular in this country and said, "I don't resent his popularity or anything else. Good Lord, I co-starred with Errol Flynn once."

Despite his praise of the Soviet leader, Reagan's prepared remarks here were in many respects a throwback to the sharp-edged anticommunist rhetoric that was once a regular feature of his speeches. It was in a speech in Orlando, Fla., in 1983 that Reagan referred to the Soviets as "the evil empire."

Many of the passages in today's speech could have been taken from that address. Reagan talked of the experience of those who have suffered "communist oppression" in Afghanistan, saying "it means parents murdered and crops, and even entire villages, destroyed in random and repeated Soviet raids. Or it means a little brother or sister whose hand was blown off by Soviet mines disguised as toys."

Reagan said he would "tell Mr. Gorbachev it is time for the Soviets to set a date certain for withdrawal, to talk with the freedom fighters and to allow the people of Afghanistan to determine their own destiny." The president said he would "also say it's time for them to leave Cambodia, Ethiopia, Angola and Nicaragua."

In addition, Reagan said he is "concerned that many more political prisoners remain in jail, internal exile and psychiatric hospitals" in the Soviet Union. He denounced the persecution of religious believers, saying that their "only crime" was an attempt to "practice their religion and worship God as they pleased."

"Well, Mr. Gorbachev and I are going to have a few words about that," Reagan added.

The president also defended his past and present rhetoric about the Soviets, reproving those who "said it was provocative to tell the truth about repression in the Soviet Union, about Soviet overseas adventures, about Soviet violations of past agreements."

Reagan said that the INF treaty demonstrated the value of this frank talk and "lots of hard work and patience."

He said that after the summit, "we will keep our negotiators working on an agreement that could lead to cutting the U.S. and Soviet long-range nuclear arsenals in half and reducing the disparities in conventional forces" between the North Atlantic Treaty Organization and Warsaw Pact nations in Europe. Reagan called the INF agreement "a first step across the open frontier towards a safer world for you and your children. And my plan -- our plan -- should be to keep right on marching."

When a student questioner asked Reagan what he would say if he could ever advise Gorbachev, the president replied: "To really stick with his program of glasnost {openness} . . . and to make their country like ours . . . {so} that people don't want to leave."