The invention relates to the field of the power electronics, and provides a standby circuit and the method for realizing the standby circuit. In the normal operating state, a first feedback loop works, the principal output voltage is normal, and devices work normally; when standby signals are present, the duty ratio of a pulse-width modulation (PWM) module is reduced through a high-voltage auxiliary winding module, so that the principle output voltage is reduced to close to zero and the electronic devices stop working, and at the same time, the high-voltage auxiliary winding module produces astandby voltage for the standby circuit, thereby entering the standby state, reducing the energy consumption and ensuring the simple circuit structure.