In recent years, two-dimensional transition metal chalcogenides (TMDCs) have been widely studied in the field of photodetection due to their excellent electronic and optical properties. Compared with the more reported field-effect transistor and heterojunction devices, homojunction devices have unique advantages in photodetection. This article focuses on the researches of photodetectors based on the homojunctions of TMDCs. First, the working principle of homojunction optoelectronic device is introduced. Then, the reported TMDCs based homojunctions are classified and summarized according to the adopted carrier modulation techniques. In addition, this article also specifically analyzes the transport process of photogenerated carriers in homojunction device, and explains why the lateral p-i-n homojunction exhibits fast photoresponse speed. Finally, the research progress of the TMDCs based homojunction photodetectors is summarized and the future development is also prospected.