An assembling jig for lens module comprises a crutch, a mobile carrier and a pressing mechanism. The crutch includes a level mounting base and an erect support wall joined to one side of the mounting base. A firm carrier is fixed on the mounting base. The mobile carrier fixed on the firm carrier comprises a carrier base, several positioning blocks disposed around the top surface of the carrier base, the positioning blocks surrounding a restraining groove in which a PCB with a lens socket is received. The pressing mechanism disposed on the support wall includes a pressing member can move up and down and a drive gear connected to one end of the pressing member. This kind of lens module component assembling jig features in assembling lens component steadily and can be applied to different kinds of lens component. Thus it abates the cost of assembling the lens component.