A power path switch circuit includes: a power transistor unit including: a first vertical double-diffused metal oxide semiconductor (VDMOS) device, wherein a first current outflow end of the first VDMOS device is coupled to an output end of a power path; and a second VDMOS device, wherein a first current inflow end of the first VDMOS device and a second current inflow end of the second VDMOS device are coupled with a supply end of the power path; and a voltage locking circuit coupled to the first current outflow end and the second current outflow end, for locking a voltage at the second current outflow end to a voltage at the first current outflow end, so that there is a predetermined ratio between a first conductive current flowing through the first VDMOS device and a second conductive current flowing through the second VDMOS device.