Abstract: Power system is a complex dynamic system. Load flow calculation is one of the most basic methods to analyze power system. It plays an important role in studying the operation mode of the system and determining the power supply scheme in the planning of power grid. Using the flow distribution data to analyze the running state of power system can improve the settings of unknown system parameters, such as the line reactance. Compared the difference between actual power flow distribution and the simulation result of PSASP, it is proved that the system parameters can be calculated accurately by using the power flow distribution data in the system where the line reactance value is far greater than the resistance value.