Parise scored his second on the power play at 11:57 to make it 5-2. He roofed a shot over Sandstrom's right shoulder from the left circle.
New York finished 2-for-3 on the power play. Philadelphia was 0-for-2.
"The theme has to be shoot, shoot," Parise said. "And we know as a penalty kill once they start shooting and you start running around a little bit you get out of your structure. I think when we're shooting the puck and hunting down the second chances and second waves, that's when we're scoring."
Adam Pelech gave New York a 1-0 lead at 4:33 of the first period, scoring on a one-timer from the left hash marks off a pass from Beauvillier from below the goal line.
It was the 18th goal scored by an Islanders defenseman this season, the most in the NHL.
"Be more aggressive and chipping in offensively when we can," Pelech said. "Defending first, that will always be our calling card."