Lucas Tang fell from a third-level luxury box in November 2010. Tang had just posed for a picture and was about 2 ½-feet away from his mother when he scampered onto a 10-inch-high ledge and dropped 30 to 50 feet.
The boy died at a hospital and an autopsy determined his death was an accident.
The suit claims Anschutz Entertainment Group (AEG) and L.A. Arena Co., which operates the downtown facility, failed to warn fans about the potential danger.
AEG has not commented.
The Associated Press contributed to this report.