In optical wireless communication system, photoelectric conversion is realized by photodetector at the receiver, and the noise in the detector will directly affect the photoelectric conversion efficiency. Based on the background of optical wireless communication, according to the generation mechanism of photodetector noise, this paper describes the shot noise, multiple generation compound noise, 1/f noise and thermal noise of the detector respectively, and gives the corresponding mathematical models. The noise models of avalanche photodetector, original negative signature detector, photomultiplier tube, four quadrant detector, quantum dot infrared detector and balance detector are analyzed respectively. Finally, the direction of further research in this field is pointed out.