With the advent of the mass tourism era and the rapid development of all-for-one tourism, the spatiotemporal distribution of tourists has undergone major changes, resulting in significant challenges to the carrying capacity of tourist destinations and the spatial structure and organization of the tourism industry. On the basis of the tourist volume data of Hangzhou obtained from passenger flow analysis sensors and Hangzhou Tourism Overview, in this paper, we visualize the spatiotemporal distribution of tourists in the past ten years and explore its evolutionary law through the research methods of kernel density analysis, standard deviation ellipses, and gray system prediction. Six factors affecting the tourist volume, namely, the number of service providers, tourism demand scale, economic development level, policy support, tourist reception capacity, and tourism resource endowment, were also probed using the GeoDetector statistical method. We found that the distribution of tourist density in Hangzhou has changed from one core to multiple cores and the overall spatial agglomeration has decreased. The trend of tourists moving westward is expected to continue. Among the factors behind this change, the number of service providers has the highest effect and the tourism resource endowment has the lowest effect. The interaction of various factors can promote the evolution of the spatiotemporal distribution of tourists.