The invention discloses a novel positioning member for a light transmission module. The light transmission module comprises a printed circuit board (PCB) and a light transmission device, wherein the light transmission device is assembled in a base through a mounting flange plate with two matched semicircular clamping grooves and the positioning member, the base is provided with a positioning hole, the PCB and the light transmission device are packaged by a shell made of a metal plate to form a light transmission module body, the positioning member transits through an inclined plane to form a conical salient at the bottom, a conical column protruding outwards to match the positioning hole is further arranged at the bottom of the salient and between the two semicircular clamping grooves, and at least two dome bosses are formed at the top of the positioning member. The novel positioning member for the light transmission module, which is novel in outline structure, is easy to assemble, higher in yield and better in stability, then reduces the production cost and the production period, and improves the yield of a product.