Sen. Joseph R. Biden Jr., the ailing former Democratic presidential candidate, on Saturday made his first public appearance since February.

Choking up and in tears at times, Biden told a party gathering, "Ladies and gentlemen , it's good to be home." The crowd of 700 at the Suffolk County Democratic Jamboree responded by chanting "Joe, Joe, Joe."Biden ended his presidential campaign in September after it was revealed he borrowed material without credit in a speech and had overstated his credentials. Then in February he was hospitalized for the first of two operations to remove life-threatening brain aneurysms.

Biden said Saturday that doctors at Walter Reed Army Medical Center pronounced him fit to return to an active life.

Biden said he plans to return to his duties as chairman of the Senate Judiciary Committee on Sept. 7, when Congress returns from its summer recess. His first task will be to chair a subcommittee hearing on the War Powers Act.

County Party Chairman Kenneth L. McDowell predicted Biden will be a candidate for re-election in 1990.

Biden said he has no presidential ambitions because he expects Michael Dukakis will occupy the White House for the next eight years.