President Reagan's foreign policy got caught in a cross fire of bipartisan congressional criticism yesterday as House Democrats and Republicans lined up to tell Secretary of State Alexander M. Haig Jr. of their confusion and dismay over such administration moves as lifting the grain embargo against the Soviet Union and deciding to sell sophisticated radar planes to Saudi Arabia.

The occasion was Haig's appearance before a House Appropriations subcommittee to testify about the administration's foreign aid program. It quickly turned into a nonstop gripe session where the members, representing a broad cross-section of congressional opinion, made clear their view that administration policy seems so erratic as to be unintelligible to America's allies and adversaries.

The criticism came not only from Democrats such as the subcommittee's cantankerokus chairman, Clarence D. Long (Md.), but also from such conservative Republican Reagan stalwarts as Jack Kemp (N.Y.) and Mickey Edwards (Okla.). Collectively, the House panel's members voiced a chorus of complaints that went on for two hours without anyone putting in a kind word for the administration's conduct of U.S. foreign relations.

Adding a richly ironic note to the situation was the fact that on the two subjects that provoked that most discussion -- the grain embargo and the Saudi arms deal -- Haig was in the position of defendig decisions that he opposed within the inner circles of the administration.

Haig had argued unsuccessfully against lifting the grain embargo on the grounds that it would undermine the administration's efforts to follow a tough line with the Soviets. He also lost an internal fight to hold off on promising the Saudis airborne warning and control systems (AWACS) planes until more groundwork was done to build congressional support for the controversial move.

Much of the confusion about administration policy has been blamed on Haig's tempermental outspokenness and his much-publicized turf battles with other senior administration officals. Yesterday, however, he worked hard at filling the role of the loyal team player -- refusing to be argumentative in the face of provocative questions, dutifully repeating the administration's standard justifications for its actions and saying again and again that he "fully supports" President Reagan's decisions.

Despite his efforts to maintain a lowered profile, Haig continues to be a major source of the controversy surrounding administration foreign policy. That was underscored anew over the weekend when he gave an interview to the Associated Press saying that in the event of Soviet aggression against Poland there would be an "across-the-boar" cutoff in U.S. trade with the Soviets.

On Monday, when White House deputy press secretary Larry Speakes was asked about the comment, he replied that Haig was discussing only "one of the many options" Reagan could resort to in the event of a Polish crisis, and added that the president repeatedly has declined to say what options he would choose in hypothetical situations.

Yesterday The New York Times gave front-page display to Speakes' statement under the headline "White House Takes Exception to View of Haig on Poland." That touched of a flurry of Washington speculation about whether there are moves afoot in the White House to ease Haig out; administration officials were forced to put out word that Speakes' comment had been intended as a noncommittal remark, that it was based on guidance prepared within Haig's own department and that there was no new disagreement between the secretary and Reagan or other administration officials.

But the incident was indicative of the "who's-in-charge?" and "where-are-we-going?" arguments that are swirling around the administration's foreign policy and that surfaced in the acerbic complaints and expressions of frustration that Haig heard on Capitol Hill yesterday.

In addition to savaging the lifting of the grain embargo as a sign of indecisiveness and the AWACS deal as a danger to Israel, the subcommittee members complained about such other front-burner issues as U.S. activities in El Salvador, allegations of a U.S. tilt toward South Africa in dealing with Namibia and alleged lack of clarity in spelling out the administration's approach to human rights.

In his responses, Haig fell back on the standard answers the administration has been using. He defended lifting the embargo as fulfillment of a Reagan campaign promise and said the Soviets were under no illusions about U.S. intentions to oppose any new aggressive behavior by Moscow.

He insisted that the AWACS deal would not harm Israel's security and said it was important both to maintain U.S.-Saudi friendship and to guard against Soviet encroachment in the Persian Gulf.

In reply to questions about whether the administration has lost interest in El Salvador, Haig asserted that the issue has moved off the front pages largely because of the administration's success in helping the goverment there resist the challenge of leftist guerrillas.