There are the problems in long approaching time and serious chattering when traditional isotropic approaching law sliding mode controller is controlling phase shifted full bridge converter, as a result, an optimized isotropic approaching law control method is proposed in order to solve the deficiency of the isotropic approaching rate, meanwhile, the state variable of inductor current is added, and the mathematical model of the phase shifted full bridge converter is given. Finally, the optimized isotropic approaching law is used to design phase shifted full bridge converter sliding mode controller, which is compared with PI controller and isotropic approaching law controller. Simulation results show that the proposed method improves static, dynamic and robust performance of the system.