President Carter said last night he will ask Congress for emergency legislation to deal with a worsening shortage of natural gas that has laid off more than 200,000 workers and closed schools attended by more than 200,000 students east of the Rocky Mountains.

The President also asked all Americans to turn their gas and oil thermostats down to 65 degrees or lower.

Carter's announcement was released 90 minutes after a White House meeting of his chief energy official, James R. Schlesinger, and 29 representatives of consumers, suppliers, regulators and Congress.

"I can pledge that the government will use the full measure of its authority to respond forthrightly to minimize the adverse effects of this situation," Carter said in a three-page statement.

"I have instructed Dr. Schlesinger to work with congressional leaders to develop emergency legislation to augment our legal means to distribute equitably our available supplies."

Carter also directed officials at all government buildings and bases to turn their thermostats down to 65 in the daytime and lower at night, and called on all Americans to do the same.

"By this action, great savings are possible," Carter said. "Without public conversation, there may not be enough energy to allocate."

The President did not spell out what kind of emergency legislation he wanted. But presumably it would force owners of intrastate pipelines in Texas and Louisiana, where prices are unregulated, to feed natural gas into interstate pipelines where prices are regulated by the Federal Power Commission. These feed gas away from the Gulf Coast states. Natural gas in Texas and Louisiana at unregulated prices is not in short supply.

Emergency legislation might also include laws to redirect the flow of natural gas from where it is plentiful west of the Rockies to where it is scarce in the East.

Yesterday's White House meeting was attended by members of the Federal Power Commission, the Federal Energy Administration, representatives of most of the big gas pipeline companies, and Sen. Adlai E. Stevenson (D-III.) and Rep. John D. Dingell (D-Mich), chairmen of the congressional subcommittees with jurisdiction over natural gas.

Carter did not attend but spoke with Schlesinger during a break in the meeting and at the conclusion.

"I I recognize the critical need for the legislative and executive branches to work together to put all the instrumentalities of government to work to alleviate this crisis," Carter said. "The industry has indicated its willingness to work cooperatively with the government in dealing with the crisis."

The bitter cold of the last two weeks east of the Rockies has triggered the worst natural gas shortage in memory in the eastern United States. Some schools have closed in 10 states and plants and factories in more than 10 have either closed or laid off workers because they can't get gas.

Worst hit are the southern states of Tennessee, Alabama, North Carolina, South Carolina and Georgia, where the winter has been the worst in more than 100 years.

Steel mills in Birmingham, carpet mills and textile companies in the Carolinas and Georgia and glass companies in Tennesse have all closed down, as have companies in New Jersey and Pennsylvania.

Early this week, 59 carpets mills in north Georgia laid off more than 7,000 workers because Southern Natural Gas Co. stopped the flow from its pipelines to the factories. The pipeline company said it had used up a 60-day supply in less than 30 days and was unable to buy emergency gas.

Natural gas is used to finish the carpets. Bottled propane gas can be used as a substitute, but it is in scarce supply in Georgia. Oil heat cannot be used because sulfur fumes ruin the rugs.

At the White House meeting, Associated Press reported, pipeline officials proposed legislation to let them allocate scarce gas supplies among themselves and to allow emergency sales of natural gas at unregulated prices for up to 180 days, an idea that was ruled out under existing law by the federal courts last year.

A participant in the meeting, former FPC Chairman Lee C. White, told the AP the pipelines have made some voluntary transfers of natural gas, but he said that as shortages deepen they want legislation protecting them against possible legal liability or after trust violations if they are to divert gas from their normal customers to other pipelines whose customers face severe shortages.

White, who now represents the Consumer Federation of America, said this proposal might be acceptable, but he had some doubts about the second proposal to authorize 180-day emergency sales above the ceiling prices set by theFPC.