Abstract: In the strategic process of deepening high-level opening-up and accelerating the formation of a new development pattern of “dual circulation”, the dual effects of OFDI on energy consumption and ecological environment in the home-country have become an important topic that needs to be explored urgently. Based on the inter-provincial panel data of China from 2004 to 2022, this paper systematically discussed the impact of OFDI on the home-country’s energy eco-effi ciency by comprehensively using the two-way fi xed eff ect model, the mediating effect model, and the threshold effect model. The results show that the impact of OFDI on the home-country’s energy eco-efficiency is a steady promotion, and the efficiency of technological innovation, the upgrading of industrial structure and economies of scale are important ways for OFDI to improve the home-country’s energy ecoefficiency. Further threshold eff ect and heterogeneity test show that the higher the degree of regional marketization, the more conducive to the improvement of the energy ecological eff ect of OFDI, while the high level of regional environmental regulation weakens the energy ecological eff ect of OFDI to a certain extent. In areas with a higher degree of industrialization and higher technology intensity, the energy ecological eff ect of OFDI is more obvious.