Former California Gov. Ronald Reagan last night urged his fellow conservatives to remain in the Republican Party and "start acting to bring about the great conservative majority party we know is waiting to be created."

Speaking in Washington for the first time since he launched his ill-fated presidential candidacy his ill-fated presidential candidacy on Nov. 20, 1975, Regan said the GOP should be reconstituted as the "New Republican Party" embracing both economic conservatives and Democratic working-class people who are conservative on the "social issues" of crime, abortion, busing and quota systems.

Essentially, this was the argument made by theorists of Richard M. Nixon's "new majority," the notion that Democrats attracted by George Wallace and other protest candidates could be added to GOP strength to win elections. This worked out in practice for Nixon in 1972, when the Democrats nominated George McGovern for President, but the Theory nas had limited success below the top of the ticket.

Reagan's message last night to a predominatly conservative audience was that conservatives are fooling themselves if they think they can create such a new majority from scratch in a new party. Instead, he said, the GOP should provide the mechanism because "the biggest single grouping of conservatives is to be found in that party."

Reagan said that the New Republican Party also must include blacks and that the GOP inability to attract blacks was the party's "major failing."

Reagan spoke before a banquet of the Intercollegiate Studies Institute at the Mayflower Hotel. A few hours earlier the Republican National Committee concluded its winter meeting at the Washington Hilton after sidetracking a proposal by a Reagan supporter to study a new name for the GOP.

But William E. Brock III, elected party chairman Friday, promised North Carolina national committee-man John East that the proposed name change would be taken up by a rules review committee.

East's proposal reflected the current low estate of the GOP.

East said southerners freqently agreed with Republican principles but that the GOP name was a barrier to them because of legacies starting with the Civil War and running through Watergate.

he offered no suggestion for a new name, saying that it should come out of a study if a new name is found to be desirable.

The national committee yesterday approved Brock's selection of Mary Crisp of Arizona as co-chairman. Crisp, who replaces Robert Carter of the District of Columbia, is popular with all wings of the party, and her selection was another indication that Brock intends to go out of his way to avoid any conflicts arising from the presidential nomination contest between Reagan and President Ford.

Crisp's selection highlighted the "Sun Belt" swing of the Republican party as it prepares to confront a southern Democratic President in the White House. Both Brock and Howard Baker, elected recently as GOP leader in the Senate, are from Tennessee. House Minority Leader John J. Rhodes, like Crisp, is from Arizona. The appeal of Reagan is heavily concentrated in the West and South.

In other business yesterday the national committee passed a resolution expressing "unalterable opposition" to amnesty for draft resisters.

Brock moved cautiously to mend fences his first day on the job. He met with defeated candidates and he said he would keep national committee executive director Eddie Mahe in charge of political operations.

Brock also indicated he would be more than willing to play the customary national chairman's role as attack man against the party in power.

In his acceptance speech Brock referred to the Democratic Congress as a majority "so rank with irresponsibility, incompetence and arrogance that it has lost contact with its constitutional role of r epresentation."

But Brock and Reagan seemed yesterday to be following a honeymoon course with President-elect Jimmy Carter. Several Republicans at the national committee said the prevailing view is that the GOP should go slow on Carter and let conflicts develop within his own Democratic coalition.

In the text of his speech last night, Reagan cited a Gallup poll of last October showing that 50 per cent of Americans consider themselves conservative or right-of-center compared with 37 per cent who think of themselves as liberal or left-of-center and 12 per cent who place themselves in the middle.

Reagan said this demonstrated that conservatism was the majority view in the nation and not "a narrow ideology" as it has been depicted. But he said that conservatives often had failed to organize effectively, to attract young people or to draw upon the academic community.

Reagan will have plenty of money to propagate his ideas in the year ahead. Lyn Nofziger, a longtime aide, confirmed that Reagan has about $1 million left over from the campaign which will be used to create a new political action committee.

The Republican National Committee has plenty of money, too, partly because the Ford campaign committee didn't make use of it. Mahe said yesterday that the committee had raised $3.2 million for the Ford campaign but that $1.8 million was never used even though the Ford committee was told it was available.