President Reagan intends to nominate George Douglas, a conservative Texas economist, to the Federal Trade Commission to bolster his administration's program to curtail the regulatory powers of that consumer-oriented agency, especially in the areas of antitrust and deceptive advertising.

Douglas' nomination, announced yesterday, may run into rough sledding in the Senate, which is expected to raise questions about his party affiliation. By law, the seat cannot go to a Republican, and Douglas is reported to have voted in the 1980 GOP primary in Texas.

Furthermore, all the Democrats and many Republicans on the Senate Commerce Committee supported Amy L. Bondurant, the counsel to ranking minority member Sen. Wendell Ford (D-Ky.), for the post.

The Douglas nomination reportedly was pushed by FTC Chairman James C. Miller III, a philosophic ally of the Texas economist and a co-author with him of a book on transportation deregulation. Miller, the first chairman in the 68-year-old history of the FTC to ask Congress to curb his agency's power, wants to limit the commission's ability to move on behalf of consumers in areas of unfair and deceptive advertising. That move was opposed by his three fellow commission members.

Although Republicans hold a 3-1 majority on the commission, Miller has been unable to hold sway on many key issues. Douglas could be expected to vote with him consistently.

Douglas, 44, is the president of an Austin firm called Southern Econometrics Inc. Before that he taught economics at the University of Texas and the University of North Carolina. He served briefly in 1968-69 as an economist in the Department of Transportation. He received his bachelor's, master's and doctoral degrees from Yale University.

The Texas economist was nominated to fill the seat vacated when Robert Pitofsky resigned in March 1981 to return to Georgetown University and join the Washington law firm of Arnold & Porter. Douglas is Reagan's second nominee for that post. The president withdrew the earlier nomination of F. Keith Adkinson, the national director of Democrats for Reagan in the 1980 campaign and a former staff aid on the Senate permanent subcommittee on investigations, when it became clear he could not win confirmation.

The question of Douglas' party affiliation arose when he voted in the 1980 Republican primary in Texas, where there is no requirement to declare a party affiliation and a person can cast a ballot in whichever primary he chooses. Douglas, however, has been quoted as saying that he was a registered Democrat in North Carolina before moving to Texas and only voted in the Republican primary there because there was no real contest in the Democratic.

Questions also have been raised by Senate Democrats interested in the FTC over a study he did at the request of the commission staff that was so heavily criticized that an agency judge refused to allow it to be used as evidence.

If confirmed, Douglas will join a commission with one liberal Democratic member, former Chairman Michael Pertschuk; one liberal Republican, Patricia P. Bailey; one moderate Republican, David A. Clanton, and Miller.