The invention discloses a unified power flow controller static state safety prevention control method; the method converts the electric power system static state safety problem into an optimization problem, and comprises the following steps: 1, firstly building an electric power system static state safety evaluation index as the optimization target function; then using a fault ranking method to rank all prevention static state safety faults; the UPFC contains four common flow control modes: constant power, voltage regulation, phase angle regulation and impedance compensation control modes; each control mode controls different features; the UPFC four common flow control modes are considered into the UPFC static state safety prevention control, thus optimizing UPFC control parameters, and optimizing the UPFC control modes; the optimization algorithm employs the particle swarm algorithm; according to calculation results, the UPFC prevention control parameter and control mode obtained by the method can obviously improve the electric power system static state safety level.