Outgoing U.S. Ambassador Vernon A. Walters says U.N. peacemaking successes last year - ending wars in Afghanistan, the Iran-Iraq war and Angola - are unprecedented in the annals of the world body.

These successes and warming U.S.-Soviet relations have made the United Nations "a better place for the United States to do business," Walters said in a farewell interview.The former deputy head of the Central Intelligence Agency said the U.S. view of the world body, once hostile and disdainful, has changed to appreciation. "If properly handled," Walters said, "the U.N. can be advantageous in promoting our goals of peace, prosperity and freedom."

"If it didn't exist, it would have to be invented."

He spoke as the General Assembly concluded its 43rd session, a dazzling year of achievements.

It was the year of the Nobel Peace Prize for U.N. peacekeeping operations, the farewell speech by President Reagan, the U.N. debut of Soviet President Mikhail S. Gorbachev and a move to Geneva to hear PLO Chairman Yasser Arafat.

Walters, 71, who has served as U.S. permanent representative here since 1985, described what he called an "extraordinarily successful" year.

"We got agreements to end the Afghan War, the Persian Gulf War (between Iran and Iraq) and the war in Angola. There is nothing like it in the annals of the United Nations," said Walters, who is being succeeded by Thomas Pickering, ambassador to Israel.

"And, God willing," Walters said, "We will shut down the Western Sahara and Cambodia wars very soon."

Walters refused to disclose his next position, but diplomats speculated he might be assigned to a European capital.

Last month, Angola, Cuba and South Africa signed agreements providing for Namibian independence from South Africa and the withdrawal of Cuban troops from Angola. A U.N. independence plan for Namibia will be implemented next year and U.N. peacekeepers and observers deployed.

Walters also said he believed the United States will pay about $400 million in arrears. He has opposed U.S. withholding of U.N. dues to protest what Washington considers U.N. bias and inefficiency, and has urged restoration of full funding.

The United Nations is far more effective today than in the past, and anti-U.S. name-calling, which flooded this forum several years ago, is virtually non-existent.

"We no longer get the `blood-sucking vampires of Wall Street draining the last drop from the toiling masses of the Third World.' That stuff is gone," Walters said.

He attributed the change almost entirely to the new international environment and improved U.S.-Soviet relations.

"In the old days, if we said it was `black,' the Soviets said it was `white,' " he said. "That's no longer there and the possibility of playing off East against West has largely disappeared."