Abstract: Under the background of regional integration, it is of great theoretical significance to explore the influence mechanism of factors such as spatial agglomeration, scale change and industrial structure on urban land use efficiency. The paper explores the influence mechanism of Yangtze River Delta regional integration on urban land use efficiency pattern evolution, so as to provide reference for formulating targeted and differentiated urban land use efficiency promotion policies. The results show that: (1) During the study period, the average efficiency from 2000 to 2018 is 1.003, which goes through a three-stage fluctuation process of “growth decline stability”. The global Moran’s I index is greater than 0, the positive autocorrelation is significant, and the spatial spillover effect and agglomeration characteristics are obvious. Shanghai, Nanjing, Hangzhou and other cities have rapid economic development and strong ability to gather migrant population. Therefore, the amount of land in the built-up areas will be revitalized, and the investment intensity of land development will be improved, and the efficiency will be high. Due to the imperfection of sustainable land use policy and the limitation of urban layout, the utilization efficiency of peripheral cities needs to be improved. (2) In the process of Yangtze River Delta regional integration, the spatial agglomeration of factors, the change of scale and the adjustment of industrial structure would have different degrees of impact on urban land use efficiency. There are also ripple effects between economic development and industrial activity agglomeration. The advanced production technology and development opportunities of the city are preferentially diffused to the neighboring cities, which is of great significance to the improvement of land use efficiency of the city and adjacent cities. Under the background of regional integration, the core cities in the Yangtze River Delta gradually transfer their industries to the surrounding cities in the process of upgrading the industrial development level and advanced level. The strong spatial spillover effect is also conducive to the improvement of land use efficiency of adjacent cities.