In this paper, the phase-shifted full-bridge (PSFB) DC/DC converter is taken as the research object, and a Super Twisting algorithm (STA) is proposed as a double-loop control method for voltage outer loop and current inner loop PI control. Compared with the traditional voltage current double closed-loop PI control method, The method proposed in this paper makes the circuit have better dynamic response, smaller voltage range and shorter adjustment time when the load changes, and the effectiveness of the control algorithm is verified by simulation experiments.