The left wing of the Democratic Party, claiming it will have one-third of the delegates to next summer's national party convention vowed yesterday to make "the democratization of corporate power" its goal in the 1980 elections.

Socialist leader Michael Harrington had 1,500 union and party loyalists on their feet and cheering with his call for price controls on major firms. "Not wage controls," he said. "Corporate monopoly price-fixing is at the root of inflation."

Convening at the Metropolitan AME Church for two days of workshops and mutual encouragement, the Democratic Agenda rehashed old victories and outlined a platform its members said they will push at the New York convention next summer.

Besides corporate price controls, that platform included mandatory bank credit for housing construction, encouragement for family farms and a comprehensive national health law. The platform also includes a comprehensive energy program that involves home heating oil price controls, and oil company "windfall profits" tax to finance mass transit and a publicly owned gas and oil corporation pattern on the Tennessee Valley Authority.

"Every one of these measures is politically possible and even popular," Harrington said. He declared his own preference for Sen. Edward M. Kennedy (D-Mass.) as a Democratic nominee, but urged the delegates to unite on the platform if not on a candidate.

"There are people in this church who were screaming at each other 10 years ago," he said, "but no Democrat can be elected president without the support of the people gathered here today."

The Democratic Agenda surfaced during the 1978 off-year Democratic convention when it pushed through rules changes giving a 50 percent share to the 1980 delegates seats to women and eliminating winner-take-all systems from the party primaries.

The Agenda members include major union leaders such as Douglas Fraser of the United Auto Workers, William Winpisinger of the Machinists Union, Jerry Wurf of the American Federation of State, County and Municipal Employes, and Murray Finley of the Garment Workers. Reps. John Conyers of Michigan, Robert Kastenmeier of Wisconsin and Ronald Dellums of California are members, as are assorted environmental, antinuclear, feminist, black and Hispanic groups.

Everyone seemed particularly delighted with the presence at a Friday night forum of Robert Georgine, president of the building trades union, repeatedly citing his attendance as evidence of broader national support than is normally given to traditional liberals.

In an interview, Harrington said President Carter has "gone past the point of no return" in the eyes of the Agenda. "We are the folks who wrote the platform he's done nothing to carry out," Harrington said. "The movement that drafted Kennedy comes from the liberal-labor wing." Harrington added that California Gov. Edmund G. (Jerry) Brown Jr. "gave up any chance to win the left" with his "off-the-wall" economic policies demanding a balanced budget.

But even Kennedy has to speak out more on national health care and tax reform if he expects to win the two-thirds of the party that is concerned about those issues, Harrington said.

In a disjointed, rambling luncheon speech, Wurf echoed Harrington's call for a united push for the platform. The candidates know, he said, that 28 percent of the voters elected President Carter. "That means they don't have to make it with 72 percent of us," he declared. "It was the oppressors who went to the polls in 1976, not the oppressed."

Some delegates said they haven't written President Carter off yet. "What is said here had to get back to him," said Bruce Toney, a subway superintendent and Transport Workers Union member from New York City. "I'm waiting to see if anything happens."