This application provides a plug-in implementation system and method. The system includes a plug-in module and a terminal software module. When the terminal software module does not include a service implementation of a first plug-in interface, the plug-in module may load a default implementation of the first plug-in interface to invoke the first plug-in interface. In this way, a plug-in may be extended to extend a service function of a terminal. In addition, when the plug-in interface is inconsistent with a plug-in function, the default implementation of the plug-in interface is implemented by using the plug-in module, so that an open-source software module can run normally, to ensure normal running of an electronic device as much as possible. Therefore, the open-source software module no longer depends on the terminal software module, and the terminal software module can be decoupled from the open-source software module.