U.N.Ambassador Andrew Young said yesterday he doesn't mind attacks by South Africa politicians because they bulster up his credbility with black African representatives at the United Nations.

South Foreign Minister R.F. Botha was quoted Sunday as saying he doesn't see how his nation can deal with Young in the future because Young called his government illegitimate.

"He couldn't deal with me before that statement Young remarked to reporters after testifing to a Senate subcommittee yesterday. He noted that Botha is running for re-election and said; "I really don't mind helping him."

"My whole approach to South African has been extremely moderate - too moderate," Young said. He said that he was picketed a week ago at the United Nations by Americans demanding more militant opposition to the white African governments.

The former Georgia congressman said he think there can be non-violent change in black rule in South Africa and contrasted this view with what he called the cynicism of some American corporations that are making no effort to head off a violent racial explosion.

Young repeated, in response to the question he gets over and over from reporters these days, that neither the State Department nor President Carter had discouraged him from speaking out on foreign policy issues.

State Department spokesman, Hodding Carter 111, fielding a long string of questions about Young, said yesterday: "There is no conflict, low-key of otherwise" between Secretary of State Cyrus R. Vance and Young.

Carter also said that the President's designation of Vice President Mondale as the leader of the administration's study of African policy "in no way diminishes the role of Ambassador Young or any other U.S. official."

When Young was asked whether Mondale's new role would take some responsibility from him, he joked: "I hope so." After reeling off a list of crises in Africa in including Ethiopia, Zaire, Rhodesia and Namibia, he said: "There's enough work there for anyone who wants to do it."

Young criticized the reporter who quoted him as saying the South African government was illegitimate.

The ambassador confirmed that he replied "yeah"when asked the question, but he objected to the reporter's having based the main part of his story on that one word.

"He makes a policy out of a grunt," Young said.

He made clear that he considers the South African government illegitimate morally because it is not representative of its people, but not illegitimate legally.

Sen. Hubert H. Humphrey (D-Minn.) hailed Young for the comments that have embroiled him in controversy affter controversy.

"There may be some who are jarred once in a while, but the whole country needs to be jarred," Humphrey told Young and urge him to keep firing verbal bullets.

Rep. Parren J. Mitchell (D-Md.), wjo appeared with Young as a witness before Sen. Dick Clark's (D-Iowa.), subcommittee on African affairs, also praised Young's outspokenness.

Young, Mitchell and witness from the Treasury and State departments urged Senate approval of a larger U.S. contribution to the African Development Fund, the low-interest loan affiliate of the African Development Bank.

Mitchell favored a commitment of $150 million in $50 million installments for the three fiscal years beginning with 1978.

Assistant Tresury Secretary C. Fred Bergsten told the subcommittee that the administration favors retaining greater flexibility in negotiations with other donor and with the African nations by not putting a dollar figure to the contribution at this time. He added that Mitchell's figure was "in the ballpark."

Young and the other witness agreed that it is in the United States' self-interest to provided more generous support to the African Development Fund.

The United States had made only 4.4 per cent of the contributions to the funds, considerly less than several much smaller industrial nations.

The United States, however, is dependent on Africa, principally Nigeria, for more than 33 per cent of its oil imports and on the continent for other essential minerals like bauxite, chrome, coblt, copper, manganese and platinum. The dependency will increase.

Sen. Charles H. Parcy, (R-111. praised the Carter administration for putting a high priority on Africa policy but said; "We've got to put our money where our mouth is."

Young said that a larger contribution to the African fund would be very beneficial to long-range U.S. interests.

Asked about human rights problems in a number of African nations. Young said the contribution to the development fund involves "the basic human right to eat."

He added that in his three months in the administration "I've not been in a single discussion of any type of assistance where discussion of the human rights of the country involved has not been a major factor in determining the U.S. approach".

The ambassador urged the senators not to adopt a House-passed admendment that required the United States to cast its vote in international lending organizations against loans to countries that violate human rights.

He said human rights are best protection and promoted if the administration can take a flexible approach. Young spoke last night to the NAACP Legal Defense Fund diinner. He promised beforehand that he would not make new headlines or new controversies because he would not speak about foreign policy issues.

Then he grinned and addded: "But, sometimes the spirit moves me."