A system architecture of a fast transfer switch is provided, which includes a main power loop configured to be connected to at least two power supplies, transfer between the at least two power supplies, and output an AC signal; a first parallel bypass module configured to output an AC signal, the first parallel bypass module including an independent power supply; the main controller is configured to, in response to detecting the abnormality of the first power supply of the at least two power supplies, adjust the AC signal output by the first parallel bypass module during the transfer of the main power loop between the at least two power supplies, so as to transfer from the first power supply outputting the AC signal via the main power loop to the second power supply of the at least two power supplies outputting the AC signal via the main power loop.