The invention belongs to the technical field of secondary equipment maintenance of power systems and discloses an AC/DC power supply isolation method for a secondary shorting test of a substation. When two ends of the shorting test in DC or AC, a shorting circuit is conducted; and when one end of the shorting test is in the AC and the other end is in the DC, the shorting circuit is disconnected, and a sound-light alarm circuit sends out a sound-light alarm signal. According to the AC/DC power supply isolation method, the problem that the AC is connected to a DC system in series due to misoperation easily generated in the shorting test in the prior art is solved and effective isolation of an AC power supply from a DC power supply during misoperation can be ensured.