President Reagan's economic policies and aims are strikingly similar to those of the British government, British Prime Minister Margaret Thatcher said yesterday.

Ironically, administration officials have tried hard to distance themselves from the "Thatcher experiment" in economic policy, since this has caused the deepest postwar recession in Britain.

Treasury Secretary Donald T. Regan this week told reporters that Thatcher had made mistakes which had led the British economy into trouble, when he was asked about the similarity between the Thatcher and Reagan programs. Office of Management and Budget Director David Stockman also has rejected the comparison and said that Thatcher did not do what she promised to do.

But the British prime minister yesterday ignored the apparent unwillingness of American officials to be linked with British policies. After receiving an honorary degree at Georgetown University, Thatcher said, "In my discussion with your president, I have been impressed with the striking similarity between our aims and our policies."

She pointed to her record in fighting inflation, although this has been at a cost of doubling in unemployment since she took office and a drastic decline in British industrial output. "We knew the transition could not be painless or smooth," she told the audience at Georgetown, After these many years of inflationary drift, the costs of recovery have to be paid." t

Earlier this week Thatcher told reporters that the United States is in better condition to implement the anti-inflation plans than Britain was. Administration officials so far have stressed the importance of fighting both stagnation and inflation. Thatcher's government has made "the permanent reduction of inflation . . . its first economic priority," the prime minister said in Georgetown.

She urged Reagan to fight U.S. inflation, saying that this was of great importance to the rest of the world which "must rely primarily on the dollar for its trade and its reserves." She added, "The dollar is our money as well as yours."

In a litany of the similar aims of the conservative administrations in Britain and America, Thatcher also said yesterday, "The president's goal is a stable price level. Ours too. The president's aim is to free the individual from government restraint. Ours too. The president's objective is to reduce public spending and cut direct taxes. Ours too."

She concluded that "both our countries are now on the right road."

Thatcher also offered four ways of dealing with the problems of the world economy:

Restoring "sound money" and stable prices through tight control of the money supply.

"Relearning the old lesson of cutting the coat ot fit the cloth," or accepting that -- with lower growth in the coming decade than during the early 1970s -- there has to be less public spending.

Preservation of free trade and resistance to lmits om imports.

A reduction in Western dependence on imported oil.