Abstract: ：Exploring the impact of spatial reconstruction and regional relatedness characteristics of the manufacturing industry on economic performance in the Yangtze River Delta (YRD) helps to understand the key significance of industrial dynamics on regional economy from the perspective of relatedness. Based on the data of enterprise registration information in 2018, this study employed spatial analysis and social network analysis methods to investigate the spatial reconstruction and regional relatedness of the manufacturing industry in the YRD. Utilizing spatial econometric models, the impact on economic performance was assessed. The main findings were as follows: （1) The spatial reconstruction and regional relatedness of the manufacturing industry in YRD exhibited significant spatial characteristics and pronounced industry heterogeneity. General manufacturing served as the main component of spatial reconstruction and regional relatedness, with Shanghai, southern Jiangsu and northern Zhejiang as the core areas of these processes. （2) The diversified agglomeration and industrial upgrading of manufacturing had a significant positive impact on economic performance. The effect of industrial transfer and regional relatedness on economic performance depended on the stage of industrial development. For industries in the stage of dispersed industrial advantages, the outflow of industries and the increase in network in-degree contributed to economic growth. Conversely, for industries in the stage of concentrated industrial advantages, the inflow of industries was beneficial to economic performance.