The 1981-82 college basketball season opens in full swing tonight with Maryland acting as host to St. Peter's College at Cole Field House and potent Atlantic Coast Conference rival Virginia in its own Cavalier Invitational Tournament.

In addition, George Mason meets Virginia Commonwealth in the second game in Charlottesville, Virginia Military visits Navy at 7:30, and the District of Columbia inaugurates its new Van Ness gymnasium against Southeastern in the 7 p.m. opening game of its Tipoff tournament. Kentucky State plays St. Paul's in the second game.

Maryland, rebuilding after the loss of stars Albert King and Buck Williams, who led the team to a 21-10 record last season, meets the Peacocks at 8 p.m. Adrian Branch, an all-America high school forward from De Matha, will be playing his first regular-season game for Maryland. He injured his hip last week, but will play. Charles Pittman, Herman Veal, Dutch Morley and Reggie Jackson will start with him.

Virginia, ranked seventh nationally, is 1-0 after last week's Hall of Fame Game victory over Brigham Young. The Cavaliers face Fairfield at 7 p.m. in Alumni Hall. Ralph Sampson and Othell Wilson have both recovered from injuries. The tournament's second game at 9 pits George Mason, 10-16 last season, against Virginia Commonwealth, the defending Sun Belt Conference champion. The Patriots have Andre Gaddy and Terry Henderson back. VCU's Kenny Stancell will match up against Gaddy.

The winners play for the championship Sunday night.

UDC unveils its new home and a potentially fine team at 7 against Southeastern. Earl Jones and Michael Britt are both excellent sophomores and freshman Al Holland joins them in the front court. Kenny Payne, a graduate of Mackin High School in the District, has transferred from Rutgers and should be the top playmaking guard the Firebirds were missing last season.

In Annapolis, Paul Evans begins his second year at the Navy helm against VMI in Halsey Field House. In a major position change, Myron Simons has moved from forward to center. VMI is coming off a 4-23 season.