The present disclosure describes a signal transmission device based on molded interconnect device and laser direct structuring (MID/LDS) technology, comprising: a shielding shell (1); and a photoelectric conversion module (2), which includes a carrier (21), an electrical module (22) and an optical module (23). The photoelectric conversion module (2) is fixed inside the shielding shell (1), wherein the first recessed structure (201) accommodates a driving chip (211), a photoelectric conversion chip (212) and an optical module (23), and the second recessed structure (202) accommodates an electrical module (22), the driving chip (211), the photoelectric conversion chip (212) and the conductive terminal (215) are electrically connected to each other, and the carrier (21) is designed by integral molding based on the MID/LDS technology. In t present disclosure, the design space in the shielding shell can be effectively saved.