Any one of a plurality of to-be-grouped devices in a power supply system reports an initial bus voltage to a topology detection device; and reports a current bus voltage after delivering a bus voltage adjustment instruction to a target reference device. The bus voltage adjustment instruction instructs the target reference device to adjust a voltage. The target reference device receives the bus voltage adjustment instruction and adjusts the voltage according to the bus voltage adjustment instruction. The topology detection device obtains the initial bus voltage and the current bus voltage of the plurality of to-be-grouped devices, and determines, based on a difference between the initial bus voltage of the plurality of to-be-grouped devices and the current bus voltage of the plurality of to-be-grouped devices, whether the target reference device and a target to-be-grouped device are connected to a same bus.