Since the breakthrough of epitaxy technology of Si-based Ge film, Si-based Ge optoelectronic devices have developed rapidly, among which Si-based Ge photodetectors are the most prominent. Because Ge can absorb the light in the near-infrared communication band and is fully compatible with the Si CMOS process, Si-based Ge detectors are almost the only choice for Si-based optical detection. This paper mainly introduces the research progresses of two common Si-based Ge photodetectors (normal incidence and waveguide coupling), including typical device structures, and the main methodes to improve the performance of responsivity and bandwidth.