As the main starting mode of pumped storage unit, the static frequency conversion starting mode has the advantages of controllable starting current, frequent starting and wide speed regulating range. When the rotor is in low speed state, the speed calculated according to the terminal voltage is not accurate. So the output electromagnetic torque error is large with the traditional control method. Firstly, the working principle of the static frequency converter system of synchronous motor is introduced. Then an improved control method of the static frequency converter(SFC) is put forward. In the low-speed phase, the open-loop control of the trigger delay angle is adopted in the rectifier circuit, so that the SFC can continuously provide sufficient acceleration torque, and the rotor can rise according to a certain acceleration. Feedforward and feedback control are adopted in the inverter circuit to make the direct current(DC) current rise rapidly and maintain at a certain level. In the high-speed phase, the double closed-loop control rectifier circuit is used to trigger the delay angle, and the inverter circuit uses the load commutation method to realize the commutation. The parameter design method of the closed-loop controller is also given, which improves the stability of the DC loop and the dynamic performance of the static inverter system. Finally, the correctness and effectiveness of the control strategy are verified by simulation.