An engine fuel consumption rate calculation method based on the carbon balance principle belongs to the technical field of engine fuel consumption rate detection. The method is characterized by including the following steps of: step 1, obtaining the flow of fresh intake air or an oil-gas mixture and the volume fraction of each carbon-containing gas component in the exhaust gas; step 2, obtaining the amount of total materials of the engine intake air per unit time; step 3, establishing a combustion model of fuels; step 4, obtaining the amount of total materials of the engine exhaust gas per unit time; step 5, obtaining a fuel consumption rate corresponding to the carbon-containing gas components in the exhaust gas; step 6, obtaining a fuel consumption rate corresponding to soot emissions; and step 7, calculating the sum of the fuel consumption rates corresponding to the carbon-containing gas components and the soot emissions to obtain an engine fuel consumption rate. According to the engine fuel consumption rate calculation method based on the carbon balance principle, the influences of fuel components, exhaust gas compositions and soot emissions are fully considered in the calculation process, errors occurring in the calculation process can be greatly reduced, and the accuracy of calculation results can be ensured.