A camera module (10) and an assembly process thereof. The camera module (10) comprises a lens (100), a lens holder (200), an image sensor assembly (300), and an anti-loosening screw for fixing the lens (100), the lens holder (200), and the image sensor assembly (300). The lens holder (200) is provided with a lens mounting hole for mounting the lens (100) and a screw hole for installing the anti-loosening screw. The lens mounting hole passes through a first surface (207) and a second surface (208) of the lens holder (200). The lens holder (200) comprises a support platform (203), a positioning guide tube (204), and an internal thread (205) sequentially arranged in a direction from the first surface (207) to the second surface (208). The support platform (203) is recessed into the first surface (207) toward the second surface (208). The lens (100) comprises an external thread (103) matching the internal thread (205), a positioning guide step (102) matching the positioning guide tube (204), and a limit ring (101) matching the support platform (203). The image sensor assembly (300) is attached to the second surface (208).