Abstract: This paper proposes a current distribution theory based on classical circuit theory.And this paper established analytical model and algorithm of the distribution factors and the extraction factors on the basis of the current distribution theory,which makes clear the power-transfer relation between generators and loads.Finally,the losses produced in the process of power transmission between the specific generator and load can be obtained by calculating the difference between the distribution power and the extracted power.The proposed method was tested on the classical IEEE 3-generator 9-bus system.The simulation results show that the algorithm is correct and effective.The algorithm provides a basis for the calculation of sharing cost of transmission facilities and the wheeling cost of power flow.