Abstract: With the shocks to global fossil energy supply and the rapid development of the new energy industry, nickel, as an important strategic metal resource, has gained increasing importance. However, a significant mismatch between global nickel resource supply and demand has emerged. How China can participate in global resource allocation through outward investment and international cooperation has become a key issue for enhancing resource security and industrial stability. To address this issue, global nickel investment project data from 2014 to 2023 are used to construct a nickel co-investment network based on complex network theory. The structural characteristics and temporal evolution of co-investment relationships are analyzed. Furthermore, a Poisson Pseudo-Maximum Likelihood （PPML） gravity model is employed to analyze the influencing factors of nickel co-investment intensity. The results show that: ①the overall connectivity of the network has improved, while its scale remains stable, and both the depth and diversity of inter-country cooperation have increased. ②The community structure evolves from an initially fragmented pattern to enhanced inter-community connections, and then to partial re-differentiation. During this process, core country pairs maintain high-intensity and stable cooperation, while other country pairs provide important support through stable medium-intensity cooperation. The United Kingdom–Japan–Philippines constitutes the most core structure, while China–France–Indonesia gradually evolves into a new potential core structure. ③Firms from different types of countries exhibit distinct cooperation patterns. Developed economies such as the United Kingdom and Japan maintain central positions in the network due to their respective advantages in capital and technology; Chinese firms enhances cooperation through resource-oriented investment; and resource-rich countries such as Indonesia improve their network positions by attracting foreign capital and technology through downstream-oriented policies. ④BITs, regional linkages, resource demand, and resource complementarity significantly promote nickel co-investment, while development differences constrain such cooperation. This study provides empirical evidence for understanding competition and cooperation in global nickel investment, and offers policy implications for stabilizing the global nickel governance system and enhancing China’s resource security.