Cops arrested a thug accused of pushing a police officer down a flight of stairs in a Brooklyn subway station tonight.

Michael Ellison, 25, is accused of assaulting a female officer at the Gates Avenue J train stop in Bushwick, police said.

Officers spotted Ellison illegally using a student MetroCard to enter the station at about 10:50 a.m. yesterday, said cops.

When the officer tried to place Ellison under arrest, he turned violent and knocked her down a flight of stairs.

The officer was taken to Wyckoff hospital, where she was treated for two broken ankles and a cut to her head that required 10 stitches.