Competition in the electricity markets requires identifying the responsibility in the use of transmission networks or the associated effects. Power Flow Tracing algorithms have been developed recently to enhance the transparence of transmission system. This paper focuses on power flow tracing procedures and provides a detailed comparison of three classified algorithms: 1) power flow tracing based methods; 2) current tracing based methods; and 3) power flow analytic methods. The advantage and disadvantage of each method are discussed. Finally, the potential applications and development of the methodology is presented for furthermore research.