Exemplary system and process for assembling a camera module are provided. The system includes a worktable, a light intensity sensor, a lens module holding device and a controlling unit. The worktable provide placement of the image sensor module thereon, thus a center of the image sensor having a coordinate value thereof. The lens module holding device can hold and move the lens module above the worktable, and it has a light source to emit parallel light that converged at a focus point, wherein the light intensity sensor can detect the focus point location and generating a signal associated with a coordinate value of the focus point. The controlling unit can receive the signal and instruct the lens module holding device to move the lens module toward the image sensor module so that the optical axis of the lens module is aligned with the center of the image sensor.