A Brooklyn man threw a glass bottle at his wife during a fight — but missed and hit their 4-year-old son in the head, police said Monday.

The man, 32, and his wife were fighting in front of 127 N. Portland Ave. in Fort Greene around 8 p.m. Tuesday.

He then hurled the glass bottle at his 34-year-old wife, but struck the child instead, cops said. The boy was treated for a cut at Bellevue Hospital.

Police are still looking for the man, who ran off after the incident.