A method for triggering a power supply module switch of a cordless electric-apparatus which includes a metal inductive area and an electrostatic inductive element comprising the following steps: when a user body approaches the device to a predetermined distance which is less than the electrostatic induction distance, the electrostatic inductive element detects electrostatic charge from the user body so as to turn a switch within the electrostatic inductive element on; a power supply module supplies power for the cordless electric-apparatus when the switch is turned on; when the user body leaving away from the cordless electric-apparatus exceeds the electrostatic induction distance, the switch within the electrostatic inductive element turns off and when the switch turns off the power supply module supplies a part power for the cordless electric-apparatus.