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.