The invention provides a rapid double power supply switch device and a working method thereof, relates to a switch used for guaranteeing power supply continuity and the working method, and can effectively solve the problems of contact arcing, electrical energy loss and the like of a conventional switch. The device comprises a frequently-used power supply, a reserve power supply, a load, a circuit breaker I, a circuit breaker II as well as a switch unit I, a switch unit II, a data acquisition module and a total control module, wherein the structure of the switch unit I or the switch unit II comprises a full control type switching element insulated gate bipolar transistor I, a full control type switching element insulated gate bipolar transistor II, an uncontrollable semiconductor device diode I, an uncontrollable semiconductor device diode II, a buffer circuit I, a buffer circuit II, a drive circuit I and a drive circuit II. Serious affects of the problems such as temporary reduction of power supply voltage, short-term voltage interruption and the like on the load are reduced, and safe and stable operation of a power supply system is guaranteed. According to the rapid double power supply switch device and the working method thereof, power supply switch time reaches a millisecond level, seamless switching can be realized, both the rapidity and the transient characteristic are ideal, and strict requirements of a sensitive and critical load on the power supply reliability and electric energy quality are really met.