A dual power switching system includes a first STS, a second STS, an inductive device, and a controller. The first STS is electrically coupled to a main power source, and the second STS is electrically coupled to a backup power source. When detecting that the main power source is abnormal, the controller detects a residual magnetic flux of the inductive device and calculates a magnetic flux difference between the predicted magnetic flux and the residual magnetic flux. When determining that an absolute value of the magnetic flux difference is less than or equal to a magnetic flux deviation value, the controller determines whether the output power meets a forced commutation condition. When determining that the output power meets the forced commutation condition, the controller turns on the second STS so that the first STS is forcibly turned off by the backup power source through the second STS.