A camera module and its molded circuit board assembly and manufacturing method are disclosed, wherein the molded circuit board assembly includes a circuit board and a molded base integrally formed with the circuit board through a molding process. The molded base forms a light window disposed corresponding to a photosensitive element of the camera module, wherein the light window is configured to have a trapezoidal or to multi-stair trapezoidal shape cross section which has diameters increasing from bottom to top to facilitate demoulding, so as to prevent damage to the molded base, and to avoid stray light.