A start-up architecture of a redundant power supply system is provided. The redundant power supply system is electrically connected to a load, and includes N+M power supplies, where N≧1 and M≧1. The start-up architecture includes a power integration backboard electrically connected to the power supplies, and a mode switching member. The power integration backboard includes an activation circuit, and has a synchronous booting mode in which the power supplies are simultaneously activated and a sequential booting mode in which the power supplies are sequentially activated. The mode switching member is electrically connected to the activation circuit, and receives a manual switching of a user to output a synchronous booting signal that controls the power integration backboard to enter the synchronous booting mode and to output a sequential booting signal that controls the power integration backboard to enter the sequential booting mode.