The study of investment networks is crucial to the promotion of regional integration. Based on the data of enterprises’ outward investment from 2005 to 2022, the nodes, patterns and structural evolution characteristics of the investment network as a whole and in different industries were analyzed using social network analysis. The investment linkage matrix was also constructed and the SLM(spatial lag model) was used to explore the externalities of the investment network. The results show that the power polarization of investment network nodes is obvious, with Chengdu and Chongqing occupying an absolutely dominant position. The investment network power of manufacturing and financial industries shows ring and fragmented distribution, respectively. The investment network pattern evolves towards multi-core equilibrium, and the manufacturing network pattern is more mature. The investment network has an obvious core-edge structure, but the difference in core degree gradually decreases. The investment network has significant positive externalities on economic growth, showing a trend of decreasing and then increasing. The manufacturing investment network has a stronger role in promoting economic growth. Consumer markets and government policies are important factors driving economic growth in local and linked cities.