An output adapting device of a plug-in power system is used to connect an output terminal of the plug-in power system with an input terminal of an electronic device, so as to transmit the power from the plug-in power system to the electronic device. The adapting device includes an output adapting terminal and an input adapting terminal respectively corresponding to the output terminal and the input terminal, in which corresponding pins of the corresponding terminals have identical potential, and at least one corresponding pair of pins of the output adapting terminal and the input adapting terminal have different potential. Furthermore, the adapting device also includes an adapting unit for adapting and outputting the power from the output adapting terminal to another pin with identical potential of the input adapting terminal. Therefore, the output terminal of the plug-in power system can be standardized for widely applying in various electronic devices.