China is the world’s largest producer and consumer of non-ferrous metals. With a characteristic of energy-intensive, China’s non-ferrous metal industry is under enormous pressure to reduce carbon emissions. Accelerating the process of technical change is an effective way to reduce the carbon intensity of the non-ferrous metal industry. Based on industry data from 30 Chinese provinces during 2005–2017, this study calculated the technical change and corresponding decompositions utilising the slacks-based measure method and the Malmquist-Luenberger index. Subsequently, the impact of technical change on carbon intensity in terms of magnitude and direction is discussed, and the mediation effects among three technical change indexes and carbon intensity are analysed. The research results show that (1) during 2005–2017, the technical change of China’s nonferrous metal industry presented an overall growth trend, mainly contributed by the magnitude technical change. Simultaneously, there was variation in the technical change among the provinces. (2) The progress of magnitude technical change could continuously reduce carbon intensity in China’s non-ferrous metal industry, whereas with a characteristic of energy-using, the biased technical change will weaken the positive impact of technical change. (3) The technical change can reduce the carbon intensity of the non-ferrous metal industry by reducing energy consumption and optimising the energy structure. These findings suggest that effective promotion of technical change requires more targeted polices to reduce regional heterogeneity. The government should also encourage non-ferrous metal enterprises to reduce overcapacity, accelerate the process of high-end industry, strengthen the secondary recycling of materials and promote the use of clean energy. •The TCH of China's NMI shows an increasing trend.•MTCH made a major contribution to the TCH.•Heterogeneity of TCH exists between different regions.•TCH can continually promote the CI reduction in China’s NMI.•Energy consumption and energy structure are important mediators.