After criticizing the government's "1,250 advisory committees and commissions" in his first fireside chat, Presidnet Carter yesterday named the first such commission of his administration - 20 persons to rate the qualifications of prospective ambassadors.

White House press secretary Jody Powell said the commission would fulfill a Carter campaign promise to "make . . . diplomatic appointments onthe basis of merit." They will consider names submitted by the Secretary of State and Carter told a visiting delegation of elected Hispanic-American officials, choose "the best qualified."

Carter picked a one-time bitter political enemy, Florida Gov. Reubin Askew, to head the commission. Askew did not endorse anyone in the Florida Democratic presidential primary last year, and then came out for Sen. Henry M. Jackson, who lost the Florida primary to Carter.

The White House did not give a breakdown but the commission includes 8 women, three Hispanics, at least two blacks, and a number of active Carter supporters, some from early in the primary campaign and some who switched to him before he won the Democratic presidential nomination.

Members include New Jersey state Sen. Anne Clark Martindell: Nancy Plaherty, the wife of Pittsburgh Mayor Pete Flaherty who is credited with delivering Western Pennsylavania to Carter: United Auto Workers President Leonard Woodcork, who has been considered for other jobs in the adminstration; Miami Mayor Maurice Ferre, who switched from Jackson to was a Carter delegate to the Democratic National Convention, as well as unofficial Carter advisers W. Averell Harriman and Dean Rusk, who were also early supporters.

Also Christine Gitlin, another Carter delegate who headed the Ohio delegation, and Maria Duran, wife of Florida Democration State Chairman Alfredo Duran, an early Carter supporter, as well as Lt. Gov. Tom O'Neill of Massachusetts, son of House Speaker Thomas P. (Tio) O'Neill.

"I want to get this away from the rearm of politics as much as possible," Carter told the visiting delegations."

The Hispanic officials came to see him to protest that only one Hispanic American has been named so far to a policy-making position in the Carter administration, and their agenda included an expression of their hope that a Mexican American would be named ambassador to Mexico.

Carter told them to submit names, which they did earlier during the transition period. "If they turn out to be the best qualified, then they will be chosen." the President said.

The White House did not have an immediate response when asked if commission members would be free to judge the candidates as they saw fit, or would be given some set of administration guidelines by which to rate them.

Carter said the commission will hold its first meeting today. He called it the "diplomatic screening commission." Its formal name is the "Presidential Advisory Baord on Ambassadorial Appointments."

The advice it gives to the President and the Secretary of State will be in confidence, , Powell said.

Asked whether the group would be "dominated" by Harriman and Rusk and others with diplomatic experience, like Republican William Seranton, a former ambassador and Pennsylvania governor, Powell said:

"I know some of these folks that you don's any my guess is they're not gonna be dominated."

The group will review candidates "for any position for which noncareer people are being considered," Powell said. Career applicants for those positions would come under the commission's security as well, he said.

Carter made only one ambassadorial appointment. Richard Gardner to be U.S. ambassador to Italy, before announcing the commission.