Abstract: The accounting of carbon emissions from enterprise electricity usage is an essential component of the enterprise carbon emission accounting system. With the advancement of electricity substitution technology, the indirect carbon emissions caused by enterprise electricity consumption will become increasingly prominent. This article conducts a comprehensive analysis of the current development of the Chinese electricity market and carbon market, along with relevant policies, highlighting the challenges that Chinese enterprises face in electricity carbon emission accounting. Considering China's national conditions, a method to calculate electricity carbon emissions using power market contracts is proposed. The essence of this method is calculating regional power carbon emission factors and residual mixed power carbon emission factors. This article utilizes sample data from electric power companies in a Chinese province for experimentation and analysis, thereby verifying the feasibility of the algorithm. The results demonstrate that this method enhances the accuracy of enterprise electricity carbon emission accounting, reflects the carbon-reducing role played by the power market, and thus avoids double counting of green energy deductions. Finally, prospects for improvements in the calculation of residual mixed factors are discussed.