Bryan Trottier scored five goals in Uniondale, N. Y., last night and tied an NHL record with four in the second period as the New York Islanders routed the Philadelphia Flyers, 8-2, for their 11th consecutive victory.

Trottier's five goals matched the Islanders' club record, which he shared with John Tonelli. Mike Bossy, who assisted on each of Trottier's five goals, also tied an NHL mark by earning four assists in the second period.

Trottier's first four goals came with Philadelphia short-handed and set an NHL individual record for most power play goals in a game.

Brent Sutter got the Islanders rolling at 1:06 of the first period when he fired a shot through the pads of Philadelphia goalie Pete Peeters from the top of the left faceoff circle.

Then Trottier took over. At 9:02, he rapped the rebound of Bossy's shot past Peeters with Philadelphia's Paul Holmgren serving a penalty, giving the Islanders a 2-0 lead after one period.

Trottier made it 3-0 at 1:04 of the second period, stuffing in his own rebound. Ron Flockhart of the Flyers interrupted the hot hand with his 25th goal of the season but Trottier quickly increased New York's lead to 5-1. The 25-year-old center beat Peeters from just outside the crease as he was falling down at 8:41, and then shoveled the puck into a gaping net 29 seconds later after Peeters left the right side open while anticipating a shot from Bossy on the left.

Brian Propp of the Flyers cut the lead to 5-2 at 10:06 before Trottier's final goal, his 35th of the season, at 18:32 from six feet out on the left side.

Hector Marini and Clark Gillies scored third-period goals for the Islanders, who have outscored the opposition, 72-26, during their 11 consecutive triumphs. The winning streak is three short of the NHL record. The Islanders also equaled a club record with their 10th straight victory at Nassau Coliseum.

Trottier's other five-goal game came Dec. 23, 1978, against the New York Rangers. Tonelli accomplished the feat last year against Toronto.