At 74 years of age, Gus Hall is the oldest candidate in the 1984 Presidential race, edging President Reagan by a year.
This is the fourth time Mr. Hall, a Communist for nearly 60 years and the party's general secretary since 1959, is heading its national ticket. In 1980, with Angela Davis, the black militant, as his running mate, he received 45,000 votes, fewer than half the number William Z. Foster obtained in the party's record year of 1932.
The Communist Party program has not changed much in a half century. At a rally at City College in New York on Oct. 21, Mr. Hall told about 1,000 supporters that there was ''absolutely nothing that is wrong with the United States that socialism will not correct or set right.''
Arvo Gus Halberg, born in Iron, Minn., to a Finnish immigrant couple who were charter members of the American Communist Party, joined the party when he was 16. After a period of training at Moscow's Lenin Institute, he returned to the United States, changed his name and participated in the Congress of Industrial Organization's organizing drive in the steel industry. Imprisoned in the 1950's
Mr. Hall served in the Navy in World War II and spent five and a half years in the 1950's in the Federal prison in Leavenworth, Kan., for ''conspiring to teach and advocate'' the violent overthrow of the Government.
In an interview at the Communist Party headquarters on West 23d Street in Manhattan, the burly party leader spoke of the emergence of a third party that, although neither Communist nor Socialist, would be ''progressive'' and ''a step in the right direction.'' He left no doubt that he preferred Walter F. Mondale for President over Mr. Reagan, whom Mr. Hall has called a ''pathological liar.''
The theme of this year's Communist Party campaign is not so much to vote for Mr. Hall as to vote against Mr. Reagan. Speakers at the City College rally criticized others on the left who argued that there was no difference between Republicans and Democrats. The Vice-Presidential Candidate
Miss Davis, now 40, is again running for Vice President on the Communist ticket. She was born and grew up in Alabama, won academic scholarships and studied with the Marxist philosopher Herbert Marcuse. In 1970 she was arrested on charges of helping three inmates attempt to escape from San Quentin Prison in California. She was acquitted two years later. She lives in Oakland, Calif., and teaches at San Francisco State University
The 1984 Communist Party platform calls for, among other things, the withdrawal of American missiles from Europe, an end to ''the criminal, undeclared wars against the people of Nicaragua and El Salvador,'' economic sanctions against South Africa and the ''public takeover of the steel, auto, machine tool and rubber industries, as well as the entire energy complex.''
Asked to cite instances of his party's disagreement with the Soviet Union and other Communist countries, he said he took a much harder attitude toward President Nixon in the Watergate scandal than Moscow did, and was an early opponent of China's ''cultural revolution.''
He said he welcomed the Solidarity movement in Poland as ''a positive step,'' and added, ''The other socialist countries should learn a lesson from it; they need more independent unions that reflect people's feelings.''
On most issues, however, he continues in the American Communist Party's tradition of support for the Soviet Union. He defended Soviet intervention in Afghanistan in 1979 as a response to what he said were ambitions of the Central Intelligence Agency in that country and distinguished it from United States activities in Nicaragua by saying, ''Two people may go into somebody else's house - but one is there to help and the other to rob.''