This paper reviews the recent progress in photonic devices application of Ge-on-Si. Ge-on-Si materials and optical devices are suitable candidates for Si-based optoelectronic integration because of the mature epitaxial technique and the compatibility with Si complementary metal-oxide-semiconductor (CMOS) technology. Recently, the realities of electric-pump Ge light emitting diode (LED) and optical-pump pulse Ge laser, Ge quantum well modulator based on quantum Stark confined effect, waveguide Ge modulator based on Franz-Keldysh (FK) effect, and high performance near-infrared Ge detector, rendered the Si-based optoelectronic integration using Ge photonic devices. Ge-on-Si material is also an important platform to grow other materials on it for Sibased optoelectronic integration. InGaAs and GeSn have been grown on the Ge-on-Si. InGaAs LED and GeSn photodetector have been successfully fabricated as well.