A House Armed Services subcommittee, in the first congressional action on the proposed withdrawal of U.S. ground forces from South Korea, yesterday approved a plan to make possible the scheduled pullout of 6,000 troops this year.

However, the plan, sponsored by subcommittee Chairman Samuel S. Stratton (D-N.Y.), would require a "basic ground combat force" of U.S. troops to remain until a political settlement is achieved between North and South Korea. Such a settlement is not in sight and is considered unlikely.

The Stratton plan, adopted 7 to 1 against the dissenting vote of Rep. Ronald V. Dellusm (D-Calif.), represents a middle course between opposing views at the Capitol about the immediate future of President Carter's troop withdrawal plan. The plans under active discussion:

Approval this year of the Carter administration request for authority to transfer $800 million in U.S. arms and equipment to South Korea over the next five years. This would have the effect of authorizing the gradual withdrawal of 28,000 American ground troops in South Korea, as proposed by Carter.

Chairman Clement J. Zablocki (D-Wis.) of the House International Relations Committee said he experts to consider the administration request as part of the foreign military assistance bill awaiting action in his committee.But Zablocki said that the prospects for approval hinge in large measure on the congressional reaction to the stil-unfolding Korean influence-pedling investigation.

The Stratton proposal to authorize the transfer to Korea of the $80 million to $90 million in weaponry now being used by the U.S. combat troops scheduled for withdrawal late this year. To minimize the political problem for legislators concerned about the Korea scandals, Stratton describes his weapons-transfer authorization as a measure to protect the remaining American troops rather than as "aid" to Korea.

No action this year on any of the $800 million "transfer package" of arms and equipment, and a request to Carter to postpone by 12 months the beginning of the pullout of U.S. combat troops.

This option, which is favored by Sen. Sam Nunn (D-Ga.), an influential member of the Senate Armed Services Committee, would leave in abeyance Carter's scandal is in the headlines but promises its consideration by Congress next year.

The arms package for South Korea is of crucial importance because the Joint Chiefs of Staff approved Carter's pullout plan last year on the explicit condition that compensatory aid to Korea be provided. American military officials and diplomats have made much of the aid package in explaining Carter's withdrawal policy to the South Koreans and other concern Asians.

A congressional failure to approve the military aid package in whole or in part might well bring a switch in the Joint Chief of Staff position, and bring the already reluctant career military into opposition to the troop withdrawal. This in turn would make Carter's plan to proceed with the gradual pullout extremely difficult politically.

Officially the Carter administration is sticking by its original proposal for approval of the $800 million and the pullout of 6,000 American troops this year. Nearly 2,000 troops described as noncombat elements have already been withdrawan by attrition and other administrative measures. But the main withdrawal of combat forces is scheduled to begin Oct. 1.

Unofficially, key members of the Carter administration are well aware that a major decision by the president on the troop withdrawal legislation will be necessary within the next few weeks.

Secretary of State Cyrus R. Vance and other top officials are reported to be abreast of the various options, but policymakers said the options have not yet been presented to Carter for deliberation and decision.

Congressional attitudes may be affected by the success or failure of House investigators to obtain information from former Ambassador Kim Dong Jo, who has been accused of seeing to pay off congressmen but who is protected by the Geneva convention on diplomatic immunity.

Kim Yong Shik, the current Korean ambassador to Washington, discussed the problem yesterday with Assistant Secretary of State Richard Holbrooke.

U.S. officials were reported to believe there is still "a fair possibility" that the Korean government and House investigators will be able to obtain information from the former envoy without breaching Kim's diplomatic immunity.