The invention discloses a multiple feed loop detection method which is applied to a power supply loop that an overhead line system and a third rail are both connected with a locomotive main driving system through isolative conduction devices. The detection method comprises the steps that first voltage of a stand-by power supply loop is obtained through a first voltage sensor; a current locomotivemain driving system is powered up by a target power supply loop, the target power supply loop is an overhead line system power supply loop or third rail power supply loop, and the stand-by power supply loop is the third rail power supply loop or overhead line system power supply loop in a standby state; when the first voltage is within a preset range, the situation that the stand-by power supply loop and the target power supply loop are powered up in series and conducted is judged, and corresponding failure treatment is made. A multiple feed loop detection system is simple in circuit and smallin occupied space, and can be applied to power supply loops provided with isolative conduction devices. When a series powered-up conductive failure occurs on the stand-by power supply loop, the firstvoltage is changed to be within the preset range, treatment can be timely conducted on the failure after the change is detected, and a protective control measure is taken so as to prevent losses frombeing enlarged.