The Reagan administration, trying to improve strained relations with Chile's military, has arranged a U.S. tour for four senior Army officers in what is hoped will serve as a prototype for a broader program of visits.

The novel trip, sponsored by the United States Information Agency, reflects Washington's emphasis on strengthening ties with the armed forces as a prelude to any transition to democracy in Chile.

It comes amid American efforts to persuade senior Chilean commanders to distance themselves from President Augusto Pinochet, the Army general who has ruled Chile for 14 years. There is widespread agreement that any peaceful change in that country will require either the active support or acquiescence of the armed forces.

While the commanders of the Air Force, Navy and national police have indicated their desire to see Pinochet leave the presidency by early 1989, the Army -- Chile's dominant security force -- has continued to support Pinochet's aspirations to run as the sole candidate in a presidential plebiscite expected next year.

U.S. officials have sought to persuade military and police officers that another Pinochet term would be likely to increase political tensions that could result in major violence.

But complicating the American pitch has been a 10-year-old congressional ban on military assistance to Chile, imposed as a response to human rights abuses. The ban, sponsored by Sen. Edward M. Kennedy (D-Mass.), has deepened resentment and anti-American sentiment in the armed forces.

Moreover, it has stopped the flow of Chilean officers to the United States for training, a process that successive administrations have said was valuable because it familiarized members of the Chilean military with U.S. life and thinking.

A year ago, Harry Barnes, the U.S. ambassador to Chile, began lobbying Congress to restore some military training funds as a good-faith gesture. "The response was: 'It's a great idea, but the timing is lousy,' " said an informed administration source.

Unable to raise sufficient support on Capitol Hill, Barnes approached the U.S. Information Agency with a request to include Chilean military officers in the agency's international visitors program, according to USIA officials.

"It's a kind of experiment," said an administration official familiar with the effort. "One hopes it will have some impact."

The move has found favor even among those who have been most critical of the Reagan administration for having avoided new economic sanctions against Chile.

"The military is going to be involved in any peaceful transition to democracy," said Gregory Craig, a senior aide to Kennedy. "Everyone shares that view. But democracy has to come soon. It may be easier to get that message across to individual officers visiting up here."

The month-long trip, which began Sept. 22, was designed to give the four participants broad exposure to civilian institutions and culture in the United States and not to focus entirely on military topics, as past programs organized by the Pentagon have. The itinerary includes visits to the United Nations, West Point and a farm in Nebraska.

U.S. Embassy officials in Santiago approved the four officers, who are understood to have been checked for any report of links to human rights abuses. They are Brig. Gen. Guido Hermes Riquelme, chief of staff of the Military Institutes Command; Col. Cesar Hugo Streitt, commander of the 10th Armored Cavalry Regiment; Col. Ricardo Gaete, chief of staff of the Austral military region, and Lt. Col. Mario Gonzalez, chief of staff of the 7th Army Brigade.