A power plug having leakage current protection function is disclosed. The power plug includes a changeover mechanism for making and breaking electrical connection between the input (line) and output (load) side of the plug, and a control circuit for detecting a leakage current and a short circuit. A reset button and a test button are provided. When the reset button is pressed, a reset shaft operates the changeover mechanism to achieve electrical connection between the input and output sides. When there is a current leakage, a short circuit or other abnormal conditions at the output side of the plug (or the input side of the appliance connected to the plug), the control circuit generates a signal to operate the changeover mechanism to electrically disconnect the input and output sides. The test button can simulate a short circuit to electrically disconnect the input and output sides.