The invention relates to a method for suppressing bias magnetism of a transformer, and in particular to a method for suppressing bias magnetism of a transformer matched with a full-bridge inverter. The problem of poor reliability or complicated hardware circuit structure of an existing bias magnetism suppression method is solved. According to the method, currents of a primary side of the transformer at a positive half-cycle peak and a negative half-cycle peak are respectively sampled, current closed-loop proportional integral differential (PID) control is performed on the currents of the primary side in a positive half period and a negative half period, a switch tube in the positive half period and the negative half period is controlled to be switched off and switched on according to a PID regulation result, so that the bias magnetism of the transformer is suppressed. The method takes a DPS processor as a basis, the bias magnetism suppression is achieved basically achieved by control software, and the control is simple; the characteristics of a static error can be eliminated ingeniously by PID control, and a bias magnetism phenomenon of the transformer can be completely and theoretically eliminated; and meanwhile, the transformer has an overcurrent protection function.