The leader of a black mayors' group praised President Carter yesterday for being "the first president in years to embrace an urban policy and to systematically try to do something to implement it. "

But despite his efforts, said Mayor A.J. Cooper of Prichard, Ala, Carter probably won't be able to do much to help the nation's cities in the face of growing inflation.

" We would like to reduce to the minimum the economic problems of any city, large or small, " Cooper said at the beginning of the fourth annual meeting of the National Conference of Black Mayors. " But I don't believe we can do it, " he said. " These problems are recurrent. That is the history of the country. "

Cooper said his organization, which represents the nation's 176 black mayors, probably will end its three-day meeting with an endorsement of Carter's anti-inflation program, even though the problem might cause farther hardship to troubled cities.

But the endorsement, Cooper said, does not mean his organization will encourage its members, most of whom represent small, poor, predominantly black towns, to make fewer demands on the federal treasury.

Rather, the purpose of the black mayors' conference and its meetings is to help members develop " grantsmanship " skills, Cooper said.

" This past year, we garnered for our members $26 million in federal aid, " he said. " We do three things for our members, and we don't apologize for any of them.

"We train black mayors to be more effective administrators. We give them the technical assistance they need to get the state and federal grants that they otherwise wouldn't get through the ' good ole boy network. ' And we provide a platform for their grievances. "

He added: " We wouldn't exist if there wasn't a need, and a lot of these mayors wouldn't be here. "

Many of the mayors who attended yesterday's meetings agreed. Mayor Cecil Jones of Tatums, Okla, said his town of 600 persons has no water or sewer lines - " just the smell of cesspools. "

" I didn't come here to play. I came here to try to find a way to get some help, " Jones said. " How would you like to sit on your front porch in the evening when a cool breeze comes along? "

Conference members said one mayor came from a town so poor that his fellow mayors had to chip in to help pay his transportation, room and board.

"A guy like that really needs to be here, " said an Ohio mayor, who requested anonymity. " He needs all the help he can get. "

But not all of the black mayors preside over destitute constitnencies. The membership includes Tom Bradley of Los Angeles, Maynard Jackson of Atlanta, Coleman Young of Detroit and Walter Washington of the District of Columbia, most of whom were expected to attend the annual meeting.

Said Cooper: " You've got to give it some balance. We have some severe problems. But most of us run for the office. There must something in it. "