Group IV material based photodetectors, such as the Si/Ge and Si/GeSn photodetectors, have the advantages of lower cost, high reliability, compatibility with CMOS technology and integration with the waveguide devices. Therefore it can be widely applied in the photo detection systems. Our recent progress on the Group IV material epitaxy and the device application on photodetectors is introduced. The emphasis is on the advance of the normal-incident/waveguide Si/Ge photodetectors, SACM avanlanche photodetectors and GeSn photodetectors.