HgCdTe avalanche photodiode (APD) array, as a new type of detector developed in the last decade, has become an important device for weak signal detection, 2D /3D imaging and active/passive detection in the future, due to its advantages of high gain, high sensitivity and high speed detection. This paper focuses on the basic principle of avalanche photodiode, and the research of HgCdTe avalanche photodiode materials and devices. In addition, the research progress in this field is reviewed.