The spatial externality of urban functional connection network is of great significance to explain interregional interconnection and mutual assistance and promote the coordinated development of regional economy. Taking 110 cities at prefecture level and above in the Yangtze River economic belt as the research object, this paper explores the urban functional network structure and its spatial effect of coordinated development under industrial connection: firstly, the urban functional structure system is constructed according to the urban industrial classification and functional characteristics; secondly, based on the perspective of industrial connection, the connection strength of urban functional network is calculated by using the modified gravity model, and the network hierarchy is determined by using the heavy tail classification method; thirdly, the social network analysis method is used to analyze the structural characteristics of various functional networks from three aspects: network spatial distribution structure, network density efficiency and network boundary effect; finally, a spatial econometric model is constructed to test the spatial effect of urban functional connection network on the coordinated development of regional economy. It is found that: 1) There are differences in the structural forms of various urban functional networks in the whole region: the functional network of circulation and public service are distributed in a jumping intertwined connection, and the other three types of functional networks are distributed in a gradient decreasing network of "dense in the East and sparse in the west". 2) All kinds of functional networks in the whole region have similar spatial differentiation: the upstream is developed in the form of Chengdu-Chongqing dual core engine; in the middle reaches, a "three pillars" axle radiation structure with the provincial capital city as the core is formed; the downstream is a flat structure with one core and multiple centers. 3) Urban comprehensive function network has positive spatial spillover effect on regional economic coordination, and this spatial effect has regional heterogeneity. 4) The sub functional networks of industrial linkages have different effects on regional economic coordination: the spillover effect of production function is the largest, and the spillover effect of circulation and public service function is not significant. 5) Under the condition of urban scale heterogeneity, the functional connection network between big cities shows negative spillover, and the functional network of small and medium-sized cities shows positive spillover. Therefore, the following policy suggestions are put forward: striving to optimize the business environment to enhance the connectivity of urban functional networks; consolidating the construction of traffic information infrastructure to release the coordination effect of functional network; optimizing the industrial division and cooperation system to avoid homogenization of urban functional positioning. Innovation: from the perspective of network externality, this paper explores the spatial effect of urban functional network on regional economic coordination based on the dimensions of regional heterogeneity, functional heterogeneity and scale heterogeneity.