The House subcommittee where the fight over decontrol of natural gas prices will begin has been transformed by changing membership from pro-regulation to a majority for some form of deregulation.

Last year the House Commerce Subcommittee on Energy had an 8-to-5 majority against deregulation of interstate gas shipments, which supporters contend is the only way to produce more gas and avoid the shortages that developed this winter. The Commerce Committee never took a vote on permanent decontrol, and when the House did by special arrangement it was rejected by four votes.

But the lineup on the expanded subcommittee now appears to be at least 10 to 9 in favor of deregulation. The margin could be greater, depending on what type bill those supporting deregulation get behind, the full Commerce Committee appears divided almost down the middle.

Rep. John D. Dingell (D-Mich.), subcommittee chairman and leading opponent of deregulation, said yesterday he hasn't counted noses on the subcommittee and doesn't know how the issue will be posed or what the Carter administration will recommend.

But Dingell is reportedly so concerned about loss of controls that he will try to get the subcommittee enlarged by three more members so he can add two friendly Democrats and get at least a tie.

Carter has promised to send Congress by April 20 an energy package that presumably will spell out his views on deregulation of natural gas. Last October, during the presidential campaign, he wrote to the governors of Texas and Oklahoma that the answer to the natural gas problem was deregulation. Since becoming President he has mentioned deregulation for a four-year period.

Dingell has promised that his subcommittee will consider permanent deregulation this year, something he did not do in the last Congress.

Eight of the nine Democrats on the Energy Subcommittee opposed deregulation last year. But one of them, Rep. William M. Brohead (D-Mich.), quit to go on the Ways and Means Committee. Rep. Bob Eckhardt (D-Tex.) had to give up his seat when he was elected chairman of the Consumer Protection Subcommittee.

Rep. David E. Satterfield (D-Va.), who voted for deregulation when the issue came to a House vote last year, lost the subcommittee chair fight to Eckhardt and then went on the Energy Subcommittee, where he is counted a vote for deregulation.

Rep. John M. Murphy (D-N.Y.), supporter of deregulation to got off the Energy Subcommittee last year, went back on. Rep. Bob Gammage (D-Tex.), a new member who supports decontrol, also went on the Energy Subcommittee.

Rep. Robert C. Krueger (D-Tex.), who was the only Democrat on the subcommittee favoring deregulation last year, now counts on support from the six Republicans, Gammage, Murphy and Satterfield to give a 10-to-9 margin for a proposal to deregulate all new (not under contract) interstate gas now and phase out controls over offshore gas prices in five years.

In addition, Rep. Timothy E. Wirth (D-Colo.), who opposed Krueger last year, vote for some deregulation formula, though perhaps less than Krueger wants.

Murphy said he is for deregulation because New Yorkers are paying $4.50 per thousand cubic feet for synthetic gas, while unregulated intrastate gas is selling in Texas for $2. Decontrol would mean cheaper gas in New York, he said.

Last year deregulation was rejected by the House in the midst of a warm winter and when a Republican President was trying to press it on a Democratic Congress. This year may be different after a cold winter if the Democratic President sends up a middleground proposal.