An optical module and a fabrication method for a hybrid InP/Si optical chip. The optical module includes a circuit board and a hybrid InP/Si optical chip. The hybrid InP/Si optical chip includes: an Si platform having a silicon photonic circuit and is formed with an InP region without a pad, a radio frequency pad and a direct current bias pad are disposed on a top of the Si platform; an InP phase modulator within the InP region, the InP phase modulator includes an InP waveguide electrically connected to the direct current bias pad and a coupling electrode disposed above the InP waveguide; and a radio frequency traveling waveguide connected, with one end, to the radio frequency pad, and the other end extending over the InP waveguide to the other side of the InP region, the radio frequency traveling waveguide is electrically connected to the coupling electrode.