A method for configuring a frequency priority, a terminal device, a base station and a core network device are provided. When the base station or the core network device configures information of a frequency priority, information of a frequency corresponding to a network slice registered by the terminal device is considered. The method includes: transmitting a first request message to a core network device, wherein the first request message is used for requesting information of a network slice registered by a terminal device; receiving a response message transmitted by the core network device for the first request message, wherein the response message includes the information of the network slice registered by the terminal device; configuring information of a frequency priority for the terminal device according to the response message; and transmitting the configured information of the frequency priority to the terminal device.