This application provides a method for determining a charger, a related device, and a system. The method includes: detecting, by an electronic device, a charging current output from a charger; when amplitude values of the charging current are a sequence of variable current, quantifying the current sequence into a binary sequence; determining whether the quantified binary sequence is the same as a prestored binary sequence; and when the quantified binary sequence is different from the prestored binary sequence, outputting prompt information indicating that the charger is a non-standard configuration charger. According to the present invention, whether the charger is a standard configuration charger is determined. This manner is simple and convenient. In addition, no specific device detection module needs to be disposed on the charger.