Accurate calculation of each province's CO2 emissions in the process of economic development is the basis of analyzing regional energy and environment efficiency and making the regional energy saving policies.Based on the theory of carbon emission flow in power systems，a method of calculating Chinese provinces' CO2 emissions from fossil energy consumption is developed proceeding from the secondary-energy terminal consumption.By considering the provincial trading of secondary energy，especially interprovincial electricity transactions under the regional grid structure，the provincial CO2 emissions from fossil energy consumption are calculated according to the energy consumption and loss of terminals.Owing to the serious unbalance of domestic energy resources distribution and energy consumption，there are a lot of interprovincial secondary energy transactions.Thus the proposed method is more rational than the traditional methods which only consider the primary energy consumption when calculating each province's CO2 emissions from fossil energy consumption.