The leader of Spain's Communist Party, Santiago Carrillo, has accepted an invitation to lecture at Yale University this fall. He will be the first West European Communist Party leader permitted to enter the United States since the advent of the Cold War.

American officials suggested that Carrillo would be issued a visa under a recent amendment of the 1952 Immigration and Naturalization Act that reversed the previously rigid rules against admission of foreign Communists to the United States on other than official governmental business.

The real significance of Carrillo's prospective trip lies in the Carter administration's new policy toward Eurocommunism, the tendency of Western European Communist parties to pursue policies increasingly in dependent from Moscow.

Equally significant is the Spanish party's decision to maintain official contacts with the U.S. government. Carrillo's acceptance of Yale's invitation indicates his desire to establish a credible image befor the American public and thus strengthen his party's domestic political position.

The United States established contacts with the Spanish Communist Party last month. American sources described the exchanges as middle-level contacts that will continue in the future.

Carrillo, who is secretary general of the Spanish party, has developed in his writings and public pronouncements an ideological line increasingly critical of Soviet-style communism.

In the past, however, the U.S. government has denied visas to several prominent Western European Communists.

In 1975, an application by Sergio Segre, a member of the Italian party's Central Committee, was turned down despite the fact that he had been invited to address the prestigious Council on Foreign Relations in New York.

Carrillo said he had advised Yale University that he could travel to New Haven in November.

A Yale University spokesman said Carrillo was offered the Chubb fellowship to spend up to one week speaking with students at the university's Timothy Dwight College. He would also make two-public appearances.

The list of recent Chubb fellows in cludes President Carter, former British Prime Minister Edward Heath, Sens. Hubert Humphrey (D-Minn.), Charles McC. Mathias (R-Md.), Daniel Patrick Moynihan, (D-N.Y.) and former Sen. Sam Ervin (D-N.C.).

In an interview last night, Carrillo said that the current contacts between the Spanish Communist Party and the U.S. government had been preceded by secret contacts in Paris during the dictatorship of the late Generalissimo Franco.

He said Manuel Azcarate, member of the leadership of the then-outlawed party, had a number of conversations with Senate Department officials.

American officials said, however, that they were "not aware" of any such meetings prior to the legalization of the Communist Party in Spain after Franco's death.

Carrillo has been subjected to sharp criticism in the Soviet press for his recent book. "Eurocommunism and the State." which has become a bestseller in Spain.

But these attacks have been muted recently, and Carrillo said that he had met a Soviet official this week who told him that Moscow wanted to put a stop to polemics. Carrillo described the talks with the Russian. Vladimir Persov, who is in charge of Moscow's relations with the Spanish party, as "an attempt at conciliation."

Carrillo's efforts to improve his party's image in the United States reflects a shrewd reading of under-current in Spain's politics.

The Spanish party, which was out-lawed at the end of the Civil War in 1939, has failed to capture the Spaniards' imagination since it was legalized in April. The party did poorly in June's parliamentary elections, winning only 20 seats in the 350-member Chamber of Deputies.

Carrillo, however, had become one of the stars of Spanish political life, presumably because of his maverick policies and his insistence on freedom of action for the Spanish party. His "creative interpretation of Marxism" has included criticism of the totalitarian aspects of Leninism.

The change in the U.S. law under which Carrillo is expected to be permitted entry into the United States is known as the McGovern amendment to the 1952 McCarren Act.

The amendment, sponsored by Sen. George McGovern (D-S.D.) and backed by the Carter administration, provides for issuing visas to Communists unless they represent a "threat to the security of the United States."

in such cases, the Secretary of State is required to submit to Congress in writing - and within 30 days - a detailed explanation about the potential threat involved.