The formation of the research methods tends to be a process of developing a science. Tourist flow is the key and bond for the whole travel system. Therefore, the improvement of the research method system for tourist flow is of great theoretical and practical significance. From synchronic and diachronic perspectives, this paper analyzes quantitative research methods of tourism flow by retrieving relevant domestic and foreign literature. Synchronically, scholars generally adopt models of reception index, primacy ratio to analyze the quality, quantity, direction, speed, strength and stability of the tourism flow with the assistance of some software like Geoda, GIS, SPSS, etc. Diachronically, scholars generally adopt models of distance decay principle, collecting and distributing degree and evenness index to analyze special features, web features, evolution features of tourism flow with the aid of some software like Arcgis, Mapinfo. The analysis reveals that interdisciplinary method has become an important means to study tourism flow, in which economics, geography, physics and psychology and so on join hands. With the development of information technology, especially the development of big data, the qualitative method based on the new data collecting technique will lead the future tourism flow research.