1. A method for dynamically implementing an application function, wherein the method comprises: sending, by a terminal device, status information comprising identification information of a client application with an old application function to a network device, the client application being installed on the terminal device, and the network device comprising a memory that stores a layout information function configuration file for achieving a new application function different from the old application function; obtaining, by the terminal device, the layout information function configuration file fed back from the network device; and creating, by the terminal device, a window and a program control based on the layout information function configuration file and establishing a link between the program control and the old application function to enable the client application to achieve the new application function, wherein the obtaining the layout information function configuration file as fed back from the network device comprises: detecting whether a version number of layout and a version number of configuration information locally stored by the terminal device are synchronized with the layout information function configuration file; and if not synchronous, downloading the layout information function configuration file.