Provided are a method for determining a terminal state, a core network device and an access network device, which are used for reducing signaling overhead and saving system resources. The method for determining the state of the terminal comprises: a core network device obtaining first information through an access network device; wherein the first information is used for indicating that at least one terminal is in a radio resource control inactive RRC Inactive state or a radio resource control connection RRC Connected state; and the core network device determining the terminal in the RRC inactive state in the at least one terminal according to the first information.