Secretary of State Alexander M. Haig Jr. arrived here tonight to join America's European allies in using the Madrid conference on the Helsinki accords as a forum to focus world attention on the Polish crisis.

Haig and the foreign ministers of most other North Atlantic Treaty Organization countries plan to use the conference, which formally resumes Tuesday, to condemn Polish military authorities and the Soviet Union for violating the human rights provisions of the 1975 Helsinki agreement. Poland has threatened to walk out of the talks if the West uses them to attack the imposition of martial law.

Following his speech here Tuesday, Haig will visit Portugal and Morocco and end his trip with an overnight stop in Romania that also bears directly on the tensions introduced into East-West relations by the military crackdown in Poland.

A senior U.S. official accompanying Haig said the visit to Romania was "the consequence of a continuing, persistent and very current request" from President Nicolae Ceausescu, who has been one of the most politically independent leaders in the Soviet-dominated Warsaw Pact.

Haig's visit, the official said, will dramatize the continuing U.S. determination to differentiate between Moscow and such East European countries as Romania, which has maintained relatively warm relations with the West.

The official would not discuss specifics of what Haig plans to do in Romania. But his trip is likely to result in some gesture of U.S. support at a time when Ceausescu is encountering economic difficulties similar to those troubling Poland and, like the Poles, is unable to make payments on large debts owed to Western banks.

Haig's first order of business, however, will center on the Madrid conference, whose purpose is to review progress on the Helsinki agreement that was signed by the heads of 35 nations in 1975. The follow-up conference here, which began 17 months ago, recessed in December shortly after the military crackdown in Poland.

At a special ministerial meeting of NATO foreign ministers last month, the United States and its allies decided to use the resumption as a vehicle for dramatizing Poland's plight by having their foreign ministers lead their delegations and speak on Poland at the opening plenary sessions Tuesday and Friday.

The Helsinki agreement is not binding on the signatory countries, which include 33 European nations as well as the United States and Canada. However, it has been considered important in East-West relations as a blueprint for regulating relations between the signatories, and it also contains provisions for respecting the human and civil rights of people in these nations.

Since all decisions at the meeting here require agreement of all participants, there is no chance of the conference formally condemning the Polish authorities for their actions.

But the opportunity that the meeting affords for the West to mount a propaganda barrage that will attract worldwide attention clearly has caused concern in the Soviet Bloc. Poland, which is scheduled to chair Tuesday's session, has threatened to refuse to attend or to possibly stage a walkout on the ground that the West's actions constitute an interference in its internal affairs.

However, U.S. officials accompanying Haig said they believe the Polish and Soviet delegations will be present because to stay away would call even more attention to their culpability for the repression in Poland.

The officials said the communist countries are more likely to respond with attacks on the West or resort to delaying tactics.

The officials also refused to comment on reported differences between Washington and its European allies. According to these reports, the United States, arguing that there cannot be "business as usual" while the repression in Poland continues, will seek an adjournment of the Madrid meeting until the fall.

The West Europeans, particularly West Germany, are understood to be arguing that the session should be continued as a means of communicating with the Soviet Bloc about the need for a resolution of the Polish situation.

Last night, U.S. officials brushed aside the idea of dissension among the allies as "tactical differences" and predicted that the West will present a united front by the time the meeting is called to order Tuesday.