Richard T. Hanna, the first congressman to face a jail term for involvement in the Korean influence-buying scandal, finally made public yesterday his side of the story - and generally supported the testimony of his former business colleague, Tong-Sun Park.

In two hours of often tedious testimony before the House Committee on Standards of Official Conduct, Hanna agreed with most of Park's earlier statements about the South Korean lobbying effort in Congress including the most controversial aspect of Park's testimony: Park's assertion that he was never an agent of the Korean government.

Hanna, a Democrat who represented a southern California district in Congress from 1962 to 1974, pleaded guilty last month to a federal conspiracy charge stemming from his involvement with Park in the Korean scheme. He could be sentenced to five years in prison on the charge.

Park, in contrast, was given immunity from prosecution on charges, including counts of conspiring with Hanna, in return for his testimony to Justice Department and congressional investigators about the influence-buying program. Park returned to his home in Seoul last week.

In his appearance yesterday - his first public discussion of the case - Hanna discussed his dealings with Park casually, sometimes joking about them. Although he referred occasionally to his "troubles," and noted at one point that he was "a man waiting to be sentenced," Hanna was a chipper, animated witness and seemed to have no qualms about reviewing the Korean case once more.

The story told closely paralleled what Park has said.

Hanna related how he and Park visited the head of the Korean Central Intelligence Agency in Seoul in 1968 to convince the Koreans that Park should be given the exclusive brokerage rights for U.S. rice sales to South Korea.

"I said Tongsun knew substantial people in Washington, including members of Congress," Hanna said. He added that he told the Korean officials that Park could use the commissions from rice sales to lobby members of Congress on South Korea's behalf.

He also testified that he had to give the Koreans an elementary course on how to deal with Congress to convince them to give Park the rice brokerage.

"If they had any economic interest tied in with a particular congressman's district, I told them they should utilize it. Or a congressman would be glad to have some publicity, or campaign help might be solicited, financing," Hanna said.

If the Koreans would offer such help, Hanna said he told the officials in Seoul, they could expect support from Congress in return.

Hanna's testimony began with a long series of detailed questions from the committee's chief counsel, John Nields, who rarely challenged any of Hanna's responses.

When the committee members were allowed to ask questions, the three Democrats present used most of their time to praise Hanna for his candor. The committee's two junior Republicans, Millicent H. Fenwick (N.J.) and Bruce F. Caputo (N.Y.), were the only members who asked probing questions.

They focused on the contradiction between Hanna's assertion yesterday that Park was "at no time . . . an agent of anybody in the South Korean government" and previous statements by Hanna suggesting he believed Park was serving the Seoul regime.

Fenwick asked Hanna about letter he wrote when he was in Congress in which he decribed Park as a "representative" of South Korean in Washington. Caputo cited a different letter in which Hanna wrote South Korea's president about "Mr. Tongsun Park's activities on your behalf."