An electronic device includes a main control system, a power key, a touch screen, and a touch screen control unit. The touch screen includes a plurality of infrared emitters, a plurality of infrared receivers and an infrared light grid comprising an infrared light beam passing through the power key. The touch screen control unit includes a scan controlling module, a detecting module, and a power controlling module. The scan controlling module periodically scans the infrared light beam passing through the power key. The detecting module determines whether a blocked time of the infrared light beam passing through the power key reaches a first predetermined time period. The power controlling module powers on or off the main control system when a time of blocking the infrared light beam passing through the power key being blocked reaches the first predetermined time period. A related method is also provided.