A senior U.S. trade official said yesterday that President Reagan wants to sign a trade bill this year but is concerned that a House-Senate conference will be unable to agree on legislation that satisfies the White House.

Deputy U.S. Trade Representative Alan Woods said the president would veto both the bill passed by the House in April and the measure now before the Senate, although there are provisions in both versions that the White House likes.

Woods made his remarks at a meeting at the Center for Strategic and International Studies as the Senate -- in its fourth week of debate -- moved toward completion of a 1,000-page trade bill. The Senate leadership indicated that it hopes to pass the bill today.

In floor action yesterday, the Senate stripped from the bill provisions that would have reorganized the federal agencies that deal with trade and industry. But it left intact a $500 million federal contribution over the next five years to Sematech, a semiconductor industry program to upgrade computer chip manufacturing techniques.

In his speech to the CSIS trade program, Woods said one of the major reasons the administration wants a trade bill this year is to get renewed negotiating authority for global trade talks now under way on strengthening the international compact the regulates world trade, the General Agreement on Tariffs and Trade (GATT).

Both the House and Senate bills contain the negotiating authority. In addition, Wood said both bills contain positive elements as well as parts the administration doesn't like.

"There are opportunities to work the problems out" in the House-Senate conference, Woods said, but they are complicated by the large number of congressional committees with a stake in the legislation.

He said it would be relatively simple to take care of the administration's concerns in sections of the bills under the jurisdiction of the primary panels in the trade field, the House Ways and Means and Senate Finance committees.

But eight other committees in the Senate and nine in the House hold jurisdiction over parts of the bills and could play major roles in the conference, which he said puts "tremendous pressure" on the Democratic leadership of the House and Senate "to work with the administration to come up with a bill that is acceptable" to the White House.

The administration has been working with both houses of Congress on the bill, but has avoided harsh comments that might polarize the debate in hope of achieving a satisfactory compromise in the conference.

The strategy has been considered a gamble for the administration, which last year succeeded in stonewalling Congress when it refused to make a deal on trade legislation, which helped prevent passage of a measure.

With the Democrats now in control of the Senate as well as the House, the White House has been forced to shift into a cooperative mode.

Looking to provisions passed by the Senate over the past three weeks, Woods pointed to a number of items that he said would have to be resolved for the legislation to be signed by the president.

Chief among them was a provision passed last week that would force companies employing 100 or more workers to give 60 days' notice of their intention to close a plant or impose mass layoffs.

Business has attacked the provision, pushed by Sens. Edward M. Kennedy (D-Mass.) and Howard M. Metzenbaum (D-Ohio), and the administration has argued that it will hurt American companies' competitiveness abroad.

On the Senate floor, however, both Republican and Democratic lawmakers have shrugged off veto threats.

Woods, though, said he believed the administration has the votes to sustain a veto despite the overwhelming 290 to 137 House majority for the legislation and substantial majorities on Senate votes, including an 87-7 vote Friday for a key provision.