In what he called his first official speech, outgoing Treasury Secretary W. Michael Blumenthal said today that the battle against inflation is going badly because too many politicans and social leaders are unwilling to come to grips with economic reality.

"To solve problems, we must see things as they really are," Blumenthal told a luncheon crowd of about 1,200 persons at the 69th annual convention of the National Urban League.

"We must see the world as it really is, like it or not -- however uncomfortable that may be for timid politicians or mindless poll watchers," he said.

Blumenthal was one of three Carter administration Cabinet members to address the league today. The other were the secretary-designate of the Department of Health, Education and Welfare, Patricia Roberts Harris, and Secretary of State Cyrus R. Vance.

Earlier, convention delegates heard Sen. Edward M. Kennedy (D-Mass.) outline several energy proposals which he said he will introduce in the Senate next week along with Sen. John Durkin (D-N.H.). Kennedy said that his energy program is designed "to improve the efficiency of the way American uses its current supplies of energy."

In what he called his "last news conference," after his speech, Blumenthal told reporters that his comments about "timid politicians" were not aimed at President Carter or the White House staff.

Blumenthal said he was speaking about "general attitude" -- particularly the attitude that equates reducing inflation with increasing unemployment.

In his speech, he put it this way:

"In this era, you need a lot more than slogans and righteousness to make social progress. I took it as my job, while in government, to fight hard and with candor for economic sanity, and I am proud of it. I will let history judge whether I have reason to be."

Social progress and sustained economic growth are virtually impossible as long as inflation is dominant, Blumenthal said. If politicans and other are serious about social progress, they will have to jettison the idea that there is a necessary tradeoff between inflation and jobs and do away with many federal controls on prices and rates, he said.

But -- and again without naming anyone -- Blumenthal warned that "the regulatory passion threatens to stage a comeback," especially in the energy field.

"It is vital to the cause of social justice that we end this reliance on regulation . . . . Regulation is a hopelessly cumbersome tool for distributing income fom the rich to the poor," he said.

The points laid out in his speech were the 'board lessons' drawn from "my recent stint in government," Blumenthal said of his 2 1/2 years at the Treasury Department. He said he is ending that without rancor or hostility toward anyone in the administration.

For his part, Kennedy said his energy proposal "will concentrate exclusively on the positive side of conservation, by insisting -- not that we use less energy -- but that we use our existing energy more efficiently in residential buildings, commercial buildings and basic industrial processes."

Kennedy said that his energy plan could save 4 million barrels of oil a day by 1990, or about eight times the savings in the Carter administration's proposal last week. His plan would "put urgently needed dollars into the (domestic) areas hardest hit by the cost of imported oil," Kennedy said.

He suggested caution in the use of nuclear energy and synthetic fuels because both have major drawbacks. "There is a sad precedent for the energy lesson we should have learned.

"Thirty years ago, the crystal ball seemed to be saying that nuclear power was the answer. And so the federal government foolishly embarked on a massive research and development program devoted almost exclusively to nuclear power . . .. Unless we can build our dispose of their waste effectively, we should not build them at all," Kennedy said. CAPTION: Picture, Sen. Charles Percy (R-Ill.) greets Sen. Edward M. Kennedy (D-Mass.) before his National Urban League speech. AP