The UPFC device in the power system can adjust the line current distribution and improve the economic cost. Therefore, the UPFC optimization configuration problem has a relatively high research value in the transmission line planning. Based on the UPFC DC power flow model, this paper ignores the power loss and reactive power, establishes the UPFC optimization configuration mathematical model with the economic cost of the generator as the objective function, and uses the Big-M method to process its nonlinear power flow equation. The method transforms integer nonlinear programming problem into a mixed integer linear programming problem that adapts to more solvers, and the installation position and capacity of the unified power flow controller in the line are optimized. The simulation calculations are carried out in Matlab using examples to verify the correctness and effectiveness of the model and strategy. This work is supported by Science and Technology Project of the Headquarter of State Grid Corporation of China (No. B3440818K005).