The invention provides a portable power supply switching device. The device comprises a power supply monitoring module, a judging module, an on-off control module and an alarming module, wherein the power supply monitoring module is connected with the judging module and used for monitoring the state of a main power supply and a backup power supply so as to generate state information and sending the state information to the judging module; the judging module is connected with the on-off control module and used for generating on-off control information and sending the on-off control information to the on-off control module; the on-off control module is used for disconnecting an inlet wire switch of the main power supply and connecting the inlet wire switch of the backup power supply according to the on-off control information; the pre-alarming module is connected with the on-off control module. The portable power supply switching device disclosed by the invention can be used for implementing switching between the main power supply and the backup power supply within a short time. The portable power supply switching device disclosed by the invention is simple and compact in structure, relatively low in cost and beneficial for large-scale application to industries.