The power supply system includes a first voltage conversion unit, where the first voltage conversion unit is an isolated voltage conversion unit, and the first voltage conversion unit is connected to a power supply, and is configured to convert a voltage of the power supply into a power supply voltage of the service board, that is, a first voltage; and a second voltage conversion unit, where the second voltage conversion unit is a non-isolated voltage conversion unit, the second voltage conversion unit is deployed on the service board, and the second voltage conversion unit is configured to convert the first voltage into a power supply voltage of a first load module on the service board, that is, a second voltage.