The large consumption of coal-based fossil energy has led to serious environmental problems. In order to reduce coal-fired pollution and improve air quality, many cities in northern China have begun to promote the project of "coal-to-electricity". Firstly, this paper calculates the power supply capacity of electric heating in northern China, and then calculates the annual replacement of electricity in the project of "coal-to-electricity". Secondly, a calculation method of annual standard coal saving and pollutant emission reduction potential of "coal-to-electricity" project based on annual replacement of electricity is proposed. Finally, taking the "coal-to-electricity" project in Xinjiang in 2017 as an example, the validity of this method is verified, which is helpful to the further popularization and implementation of "coal-to-electricity" project in the future.