The present disclosure provides a lens module. The lens module includes a lens barrel; a lens group accommodated in the lens barrel, the lens group including at least a first lens; and a retaining member located an image side of the lens group. The retaining member is a hollow ring which includes an object side leaning and connecting to the first lens, an image side opposite to the object side, an outer side and an inner side connecting to the object side and the image side, and the inner side is a Lambertian surface through Lambertian treatment.