This paper shows what modern Chinese dialects, ie, modern Chinese dialects, have to do with the study of Old Chinese, and looks at what is controversial in its reconstruction. In the end, it aims to reconsider what the study of Old Chinese should be. Chinese dialects have been settled as one of the essential language resources in the reconstruction of Old Chinese. They can be regarded as completely changing the flow of Old Chinese reconstruction after the acknowledgment in that they provided an opportunity to overcome the limit of depending on only written sources. It is expected to contribute to the study of Old Chinese with both the reconstruction of proto forms of modern dialects as well as ethnic languages around China.