A grown man smacked a 6-year-old boy in the head in an unprovoked attack at a Queens playground, police said Thursday.

The NYPD released cell phone footage of the suspect taken by the victim’s shocked mother and asked the public’s help identifying him and tracking him down.

The boy was taken to an area hospital but not badly hurt.

The stranger slapped the boy in the back of the head for no apparent reason at the Public School 144’s community playground on Kessel St. near 70th Ave. in Forest Hills about 6 p.m. Monday, cops said.

He stormed off without saying a word — but not before the victim’s quick-thinking mother managed to record him on her phone.

Anyone with information is asked to call Crime Stoppers at (800) 577-TIPS. All calls will be kept confidential.