A standby mode switch system includes a mode selection module, a control module, and a position detection module. The mode selection module has a vibration mode. The control module is in communication with the mode selection module and the position detection module. The control module turns on the vibration mode when the mode selection module selects the vibration mode and an incoming call. The control module turns off the vibration mode when the position detection module detects a distance from the position detection module to an adjacent object element is greater than a predetermined value.