A homeless man was fatally stabbed in Queens yesterday coming to the aid of a woman who was being robbed, cops said.

The woman was walking on 144th Street in Jamaica at 7:20 a.m. when two thugs accosted her from behind and “one of the men tried to grab her wallet,” said Alex Perez, who saw the incident replayed on a surveillance video from a nearby building.

The homeless man tried to intervene and was knifed several times in the chest, police said.