Based on a theoretical analysis of the impact of internet development on energy efficiency, a calculation has been made of the level of internet development and energy efficiency in 30 provinces of China from 2008 to 2017 by using the entropy weight method and DEA (data envelopment model), followed by an empirical test of the influence effect and mechanism of internet development on energy efficiency. It is found that the average value of internet development index and energy efficiency in China is 3.38 and 0.56 respectively, with a large gap between internet development level and energy efficiency among provinces, showing a decreasing trend in the eastern-central?western region. Using the fixed-effect model regression, the results show that the development of the internet has a positive effect on the source efficiency, which is significant at the significant level of 5%; every 1% increase in internet development level will lead to 1.8% increase in the energy efficiency; the intermediary effect of internet development 31 to improve energy efficiency through industrial upgrading accounts for 48.85% of the total effect. In terms of control variables, trade openness, energy structure and foreign direct investment have a positive effect on energy efficiency, while government intervention and R & D investment have a negative effect on energy efficiency. In the robustness test, the conclusion is still valid by replacing the core explanatory variables.