In order to deal with the new situation and achieve the goal of great rejuvenation of China, the regional integration development of the Yangtze River Delta has become a national strategy. What is the level of urban integration in the Yangtze River Delta, what obstacles it faces, and what measures shall be taken to promote integrated development – all of these are questions that need to be answered. Based on the systematic review of relevant theories, this paper constructs an evaluation index system of urban coordinated development capacity in the Yangtze River Delta, which includes 18 indexes in the four fields of economy, science and technology, facilities and ecology. Through the calculation of the collaborative development capacity of 41 cities in 2020, it shows that the “core- edge” spatial structure based on the “Z” shaped development axis in the Yangtze River Delta is significant, the degree of spatial integration is high, and the contribution and relationship of various fields to the urban collaborative development capacity are not exactly same. According to the current situation of the pattern of coordinated development of cities in the Yangtze River Delta, this paper puts forward some policy suggestions, such as reforming the public management system and mechanism in the Yangtze River Delta, innovating the cross-border linkage mechanism of environmental protection, paying attention to the linkage between new infrastructure, urban agglomeration and industrial system, establishing the Yangtze River Delta industrial innovation foundation, focusing on the construction of world-class industrial clusters of integrated circuits and biomedicine.