The invention discloses a flexible constraint layer for laser shock reinforcement online repair and a manufacturing method of the flexible constraint layer. The flexible constraint layer is prepared from bisphenol-A type epoxy resin and an amine curing agent according to a mass ratio of (1.5 to 3) to 1. The invention also discloses a manufacturing method of the flexible constraint layer for lasershock reinforcement online repair. The flexible constraint layer disclosed by the invention can be applied to a planar region, and also can be applied to a complicated curve-surface region; the manufactured constraint layer can effectively enhance the laser shock effect, and the process is stable and low in cost; and the maintenance efficiency of a machine can be effectively improved.