The invention relates to the field of communication and discloses a method and device for replacing a theme based on Android system application. The scheme is that when an instruction for triggering theme file replacement is received, a corresponding theme packet corresponding to the instruction is downloaded; after the downloading is successful, the theme packet is analyzed, a resource file contained in the theme packet is obtained; a target resource file is selected in the resource file, and the resource file contained in the theme file used currently is replaced according to the target resource file, so as to finish the theme replacement operation. Therefore, after being downloaded, the theme packet does not need to be installed and directly undergoes analysis operation, and the method not only can accelerate theme packet analysis speed and improve theme replacement speed, but also is convenient to operate and flexible in theme replacement mode.