Abstract: Coal oxy-fuel combustion technology is of great practical significance for efficient carbon reduction in coal-fired power generation. However, there is no clear accounting method for carbon emission reduction in coal oxy-fuel combustion generation project. This study refers to the norms of the Clean Development Mechanism (CDM) and the general ideas of greenhouse gas (GHG) emission reduction methodology, and establishes the accounting boundary by determining the baseline scenario. Then the author calculates the carbon emission according to the characteristics of the carbon emission in accordance with the two phases of stationary source combustion and flue gas desulphurization. After that, the author uses the methodology tools to demonstrate the additionality of the coal oxy-fuel combustion generation project, and the results show that the project activity still needs the support of the relevant carbon emission reduction and trading policies to be sustained, which is still far from the mature commercial operation. The project activity has additionality. Combing with the practical application scenario of the carbon flow and accounting methodology, it determines the main accounting process of carbon emission in the process of the project activity, and provides methodological support for the verification of carbon emission reduction in coal oxy-fuel combustion generation projects and the formulation of carbon trading policies. Finally, the methodology is applied to calculate the annual carbon emission reductions of up to one million tones generated by the retrofit of 2×300 MW coal-fired generating units with oxy-fuel combustion technology.