The orchestra of the New York City Opera last night voted 49 to 1 to return to work at the NYCO under the terms dictated by the Opera Company's management for the two-month season beginning Sept. 7.

The orchestra will receive no wage increase and will give up certain fringe benefits.

The musicians voted to extend the basic terms of the old contract--which expires next week--through the end of the season after the NYCO said it was in financial distress and could grant no additional money to its performers. The company also canceled its spring season, originally set for February-May 1983.

Max L. Arons, president of New York Local 802 of the American Federation of Musicians, said, "The reason the orchestra is going along with the NYCO is that we don't want to be the people management points to as having closed the opera for good."

The NYCO has fallen far and fast. As late as late spring its management painted a rosy future for it and was asking President Reagan to declare it "America's National Opera." Since then, however, the company's poor critical reception, its loss of audience and its financial difficulties have caused it to retrench to the point where on Thursday its general director, Beverly Sills, reportedly warned the musicians that the company was having problems meeting next week's payroll.