President Reagan, heading a contingent of about 600 Americans, will meet five times with Mikhail S. Gorbachev during next week's Moscow summit meeting, which is expected to be heavy with symbolism and ceremony. In an important way, Reagan's main audience in Moscow will not be Gorbachev at all, but the Soviet people who meet him in a variety of settings outside the formal conferences, or see him on television.

Reagan's aides are playing down expectations that the meetings will produce substantive achievements. "This is not a high-water mark," Rozanne L. Ridgway, assistant secretary of state for European and Canadian affairs, cautioned reporters.But the four-day visit is the first by an American president to the Soviet capital in 14 years. Reagan will visit monks at a monastery, students at a university and writers at a club - all events designed to give visible encouragement to changes in Soviet intellectual and religious life, while providing the striking television images that have become the hallmark of the Reagan presidency.

"It's important to talk to the Soviet people, to make them part of this," said Tom Griscom, director of White House communications. "This is their chance to hear directly from the president of the United States."

The Reagan administration is clearly disappointed that it has failed to reach agreement with the Kremlin on a new treaty reducing long-range, or strategic, missiles.

Planners had long hoped that signing such a pact would be the centerpiece of the Moscow meeting, but as those hopes have faded, the administration has focused attention on completing negotiations before the end of the year.

"I think it is possible that we could have that, yes, while our - this administration is still here," the president said.

At a minimum, the White House would like to be able to exchange documents in Moscow ratifying the treaty, signed at the Washington summit meeting last December, banning intermediate-range missiles. That treaty has encountered snags in the Senate, however, and Howard H. Baker Jr., the chief of staff, said Saturday that it "will be a tight squeeze to see it the Senate does complete action on that before the president reaches Moscow."

In his radio address Saturday, the president praised the Senate for beginning debate on the treaty and expressed the hope that it would be approved "in time to bring it into force during my meetings with the general secretary in Moscow."

Time has been set aside at the end of the summit meeting for the two leaders to sign any agreements that are produced, and a few minor pacts are being prepared to fill that session and convey an air of progress, particularly if the intermediate-range treaty is not ready.

One agreement likely to be ready for signing in Moscow would require both sides to give each other notice of any nuclear missile tests. A second possible agreement would spell out verification procedures for peaceful nuclear explosions. A third potential pact would codify procedures for carrying out experiments at nuclear test sites.

Ridgway added that a number of agreements are nearing completion in the maritime area, including ones covering search and rescue procedures, ocean pollution, transportation technologies and fishing rights.

The official also raised the possibility that a new three-year cultural agreement could be approved in Moscow. And in a speech to the graduating class at the Coast Guard Academy last week, Reagan expressed his desire to encourage more student exchanges between the two countries.

"I hope that more Soviet young people can view first-hand America's democratic system and way of life," he said.