Mike Bossy scored two goals and assisted on three as the New York Islanders defeated Philadelphia, 8-6, last night in Uniondale, N.Y., stopping the Flyers' 13-game National Hockey League winning streak.

Bossy's 11th goal of the season capped a three-goal burst in the first period, and the Islanders right wing scored the clinching goal in the third period as New York held off a comeback by the Flyers, who trailed by 5-1 in the second period.

The loss was the first in four games for the Flyers since the death of goalie Pelle Lindbergh in an automobile accident. The Flyers finished two short of the NHL record for consecutive victories, set by the 1982 Islanders.

The Flyers scored first on a 40-foot slap shot by Ed Hospodar at 5:27 of the first period. Rookie Bob Bassen, recalled from the minors Monday, tied the score with a 15-foot wrist shot past goalie Darren Jensen at 10:03, and Pat LaFontaine put the Islanders ahead for good as he flipped the puck over Jensen's shoulder in front of the net at 13:08. Bossy made it 3-1 at 15:12 on a high shot.

Bossy assisted on goals by Islanders captain Denis Potvin and Greg Gilbert in the first minute of the second period, making it 5-1.