Embodiments of the present invention disclose a network switching method, a version upgrade method, and a terminal device, which relate to the field of communications technologies. A terminal receives a user instruction that instructs the terminal to access a network of a target operator. If an operator of a network currently accessed by the terminal is different from the target operator, a preset file is read to obtain image information corresponding to the target operator. A target image file corresponding to the target operator is obtained according to the image information and version switching is performed according to the target image file. The preset file includes image information that corresponds to all image files of operators stored in the terminal in one-to-one correspondence.