A terminal device location determining method and a device. A core network device obtains location information of a terminal device reported by the terminal device and location information reported by a first base station. The core network device determines whether the location information of the terminal device matches the location information reported by the first base station, and if the location information of the terminal device does not match the location information reported by the first base station, the core network device sends a reject message to the terminal device. By determining, through comparison, whether the location information of the terminal device reported by the terminal device matches the location information reported by the base station, it can be determined whether a location of the terminal device is incorrectly determined.