The invention relates to the technical field of IGBT driving devices, and discloses a push-pull isolated power supply for an IGBT driving device and a method. The push-pull isolated power supply adopted in the method is formed by connecting a self-excitation push-pull circuit and a rectification and output circuit through a push-pull transformer. According to the rectification and output circuit, one end of a secondary winding of the push-pull transformer is connected with one end of a series capacitor through a rectifier diode, the dotted terminal of the secondary winding is further connected with the other end of the series capacitor through a rectification circuit with a voltage clamping function, and the other end of the secondary winding of the push-pull transformer is connected with a center connecting point of the series capacitor. The circuits of the isolated power supply are simplified, and the amplitude of negative voltage output by the isolated power supply is controlled. Meanwhile, the distributed capacitance of the primary side and the secondary side of the transformer is easier to control, and the common mode rejection capability of the driving device is greatly improved; the anti-interference capability of the driving device is improved. Thus, the push-pull isolated power supply is high in reliability, low in cost and small in size.