An optical transmission module includes a semiconductor substrate, a first film layer, an electronic component layer and a waveguide structure. The electronic component layer is used for converting a first electrical signal into an optical signal. The waveguide structure is formed on the first film layer, and includes a first reflective surface, a waveguide body and a second reflective surface. After the optical signal is transmitted through the semiconductor substrate and the first film layer and enters the waveguide structure, the optical signal is reflected by the first reflective surface, transmitted within the waveguide body and reflected by the second reflective surface. After the optical signal reflected by the second reflective surface is transmitted through the first film layer and the semiconductor substrate and received by the electronic component layer, the optical signal is converted into a second electrical signal by the electronic component layer.