A switching power supply saving system includes a power interface, a power converting circuit, a relay, a relay driving circuit, a trigger, and a timing sequence circuit. The power converting circuit is configured to receive the AC power from the power interface. The power converting circuit is capable of transforming the AC power to direct current (DC) power to supply to a motherboard. When the timing sequence circuit receives a power on signal, the timing sequence circuit is capable of controlling the relay driving circuit via the trigger to cause the relay to connect the power converting circuit to the power interface. When the timing sequence circuit receives a power off signal, the timing sequence circuit is capable of controlling the relay driving circuit via the trigger to cause the relay to cut off connection between the power converting circuit and the power interface.