A multi-mode wireless transceiver and a multi-mode switching method thereof are disclosed to provide at least one wireless transceiving interface capable of dynamically switching between multiple frequency bands. The wireless transceiver comprises: a first RF transceiving circuit for transceiving RF signals of a first frequency band; a second RF transceiving circuit for transceiving RF signals of a second frequency band; a first frequency synthesizer and a second frequency synthesizer for generating a first carrier of the first frequency band and a second carrier of the second frequency band respectively; and a switching circuit for outputting the first carrier to the first RF transceiving circuit, and for determining to output one of the first and second carriers to the second RF transceiving circuit according to a control signal.