A power supply protection system includes at least one of: a PSE proximal-end protection module (10), arranged at a proximal end of a PSE chip and configured to protect each pin of the PSE chip in a sudden change process of a voltage and current of a proximal-end power loop of the PSE chip; a PSE distal-end protection module (12), arranged between the proximal end of the PSE chip and a PSE network port and configured to suppress interference from a network cable and a network port and reduce a sudden change of a loop of the PSE chip into a range bearable for a proximal end of PSE; a PD distal-end protection module (14), arranged between a proximal end of a PD chip and a PD network port; and a PD proximal-end protection module (16), arranged at the proximal end of the PD chip.