Abstract: A current overload detecting system and method applicable in a data processing device connected with a plurality of electronic devices is disclosed, each of the electronic devices having a USB interface. The data processing device has a plurality of USB ports corresponding to and connected with the USB interfaces, a plurality of USB control units for controlling the operations of the USB ports, and a basic input/output system (BIOS) for executing a POST process. The current overload detecting system includes a signal-detecting unit for detecting if the USB control unit of the data processing device is outputting an over-current when the BIOS of the data processing device is executing the POST process, outputting a control signal if the USB control unit is detected to be outputting the over-current signal; and a display unit for receiving the control signal and displaying corresponding messages according to the control signal.