Based on the principle of proportion sharing and Kirchhoff's theorem, this paper proposed a efficient power flow tracking analytical algorithm. According to the calculation results, this method can generate the down-flow and counter-flow matrix, and obtain single source or single flow coefficient through the Gaussian elimination method. The proposed method can avoid the inverse matrix in the past analytical algorithm, greatly reduce calculation burden, and provide the power flow tracing parallel algorithm, which provide a basis for the application of power flow tracing in large scale power grid. This paper test the correctness of the proposed method in 2 machine 4 node test system, and prove the efficiency in several real power grids.