Condemning the Reagan administration's record on civil rights and social justice, former vice president Walter F. Mondale today issued a partisan appeal to the country's largest Hispanic organization to use its growing voting power "to return this country to a sound course of justice."

Addressing the annual convention of the League of United Latin American Citizens (LULAC) here, Mondale noted the absence of any top officials from the administration, and said, "I don't know how you lead a nation and ignore 20 million people . . . . It's time those who lead this nation not only listen to--but are accountable to--that group."

LULAC is deciding whether to jump headlong into politics by forming the first national Hispanic political action committee. Creation of such a committee has been approved by the group's executive committee, and is to be voted on by the membership during the convention.

"It's critical that we do it," said Arnold Torres, LULAC's national executive director. "It's the thing that can get us into the 20th century. Without it, we will stand still."

Torres said that if the membership approved formation of the PAC, he hoped to raise $100,000 for use in political races this fall.

Mondale, who has made numerous trips to Texas in the past 18 months in preparation for a possible presidential campaign in 1984, attacked Reagan for attempting to dismantle the Civil Rights Commission, for slowing the efforts of the Equal Opportunity Commission, for killing bilingual education while supporting the tax-exempt status of segregated schools and for failing to appoint more Hispanics to top posts.

"We've got to stand up and get that vote out" in 1982 and 1984, he said. "We have to get a sense of power again. That power is . . . waiting to be used."

Mondale's appeareance was preceded by a discussion on immigration reform that demonstrated the political power Hispanics now exercise on certain public policy issues.

The congressional co-sponsors of immigration reform, Sen. Alan K. Simpson (R-Wyo.) and Rep. Romano L. Mazzoli (D-Ky.), pleaded with the Hispanic audience to support their bill, "warts, pimples and all," and warned that failure to approve legislation soon could bring an onslaught of nativism, racism and meanness.

The bill would give permanent-resident status to millions of illegal aliens, penalize employers who knowingly hire illegal aliens and require a form of identification to be presented by all Americans and aliens when they begin new jobs.

LULAC and other Hispanic groups oppose the legislation, which the Senate Judiciary Committee and a House Judiciary subcommittee have cleared. Chances of passage this year are fading.

"The bill that is on the table will increase discrimination, it will increase harassment," said Antonia Hernandez of the Mexican-American Legal Defense and Education Fund. "We Hispanics don't want to be the only ones to pay for the betterment of society. We are Americans too."

The absence of top administration officials at the LULAC convention was especially significant in this election year because the Republican Party has said it hopes to attract a growing share of the Hispanic vote.

At the meeting last year, Vice President Bush took LULAC to task for failing to support the administration's economic program.