The invention discloses an optical module which comprises an optical diaphragm, a frame and a limiting block. The optical diaphragm contains a main body part, a connecting part and a lug, wherein the connecting part connects the lug with the main body part. The frame contains a bottom plate for bearing the optical diaphragm, and a sidewall which surrounds the edge of the optical diaphragm and is provided with a notch which separates the sidewall of the frame. The limiting block is arranged on the sidewall of the frame and extends from the sidewall to cover part of the notch. Besides, the lug is embedded in the notch and limited between the bottom plate of the frame and the limiting block.