The large-scale population mobility between cities reflects the correlation between cities to a certain extent. This paper selects the national population migration data during the Spring Festival from 2015 to 2018 in the Tencent migration database and uses Gephi software to conduct visualization analysis to obtain the strength of population connections between the cities as well as the evolutionary characteristics of the overall pattern of inter-connectivity strength. The DBSCAN algorithm is used to cluster the time series of cities across the country, and the commonalities and differences in urban mobility at different time nodes during the Spring Festival are discussed. And the distance attenuation effects of intra-provincial and inter-provincial population flow are analyzed from the improved gravity model. The results show that: (1) The national cities have formed a stable “diamond” structure as a whole, Beijing, Shanghai, Xi’an, and other cities have formed a single-axis spatial organization model, Guangdong and Shenzhen have formed a multi-axis spatial organization model, and the first-tier cities have strong centrality. In addition to cities with a “diamond” structure, cities in the northwest region and cities in the northeast region have strong advantages in terms of transit and acceptance capabilities. (2) The changing trend of net migration population during the Spring Festival was relatively stable, and a symmetrical inflow and outflow were formed before and after the Spring Festival. (3) The flow during the Spring Festival travel period conforms to the law of distance attenuation. With the increase in distance, the attractiveness of the city gradually decreases.