A notification method, comprising: configuring, by a first base station, a first cell identity for a first cell, wherein the first cell identity comprises a first identifier field and a second identifier field, wherein the first identifier field and one or more reserved bits in the second identifier field are used to identify the first base station, and one or more remaining bits in the second identifier field are used to identify the first cell; and notifying, by the first base station, a second base station or a core network device of a part of the first cell identity that is used to identify the first base station; wherein the notifying, by the first base station, a second base station or a core network device of a part of the first cell identity used to identify the first base station comprises: sending, by the first base station, the first cell identity to the second base station or the core network device; and sending, by the first base station, first indication information to the second base station or the core network device, wherein the first indication information is used to indicate a location of the part of the first cell identity used to identify the first base station; wherein the first cell identity comprises 28 bits, the first identifier field comprises 20 bits, the second identifier field comprises 8 bits, and the one or more reserved bits in the second identifier field comprises Y bits, wherein 1≤Y<8 and Y is an integer, and wherein when a quantity of base stations that need to be identified is limited in a communication process, the first base station combines the reserved bit in the second identifier field originally used to identify the first cell in the first cell identity with the first identifier field, thereby identifying the first base station by using a combination of the reserved bit in the second identifier field and the first identifier field, wherein the reserved bit in the second identifier field is Y high-order bits in the second identifier field, and Y is less than the length of the second identifier field. configuring, by a first base station, a first cell identity for a first cell, wherein the first cell identity comprises a first identifier field and a second identifier field, wherein the first identifier field and one or more reserved bits in the second identifier field are used to identify the first base station, and one or more remaining bits in the second identifier field are used to identify the first cell; and notifying, by the first base station, a second base station or a core network device of a part of the first cell identity that is used to identify the first base station; wherein the notifying, by the first base station, a second base station or a core network device of a part of the first cell identity used to identify the first base station comprises: sending, by the first base station, the first cell identity to the second base station or the core network device; and sending, by the first base station, first indication information to the second base station or the core network device, wherein the first indication information is used to indicate a location of the part of the first cell identity used to identify the first base station; wherein the first cell identity comprises 28 bits, the first identifier field comprises 20 bits, the second identifier field comprises 8 bits, and the one or more reserved bits in the second identifier field comprises Y bits, wherein 1≤Y<8 and Y is an integer, and wherein when a quantity of base stations that need to be identified is limited in a communication process, the first base station combines the reserved bit in the second identifier field originally used to identify the first cell in the first cell identity with the first identifier field, thereby identifying the first base station by using a combination of the reserved bit in the second identifier field and the first identifier field, wherein the reserved bit in the second identifier field is Y high-order bits in the second identifier field, and Y is less than the length of the second identifier field. sending, by the first base station, the first cell identity to the second base station or the core network device; and sending, by the first base station, first indication information to the second base station or the core network device, wherein the first indication information is used to indicate a location of the part of the first cell identity used to identify the first base station; wherein the first cell identity comprises 28 bits, the first identifier field comprises 20 bits, the second identifier field comprises 8 bits, and the one or more reserved bits in the second identifier field comprises Y bits, wherein 1≤Y<8 and Y is an integer, and wherein when a quantity of base stations that need to be identified is limited in a communication process, the first base station combines the reserved bit in the second identifier field originally used to identify the first cell in the first cell identity with the first identifier field, thereby identifying the first base station by using a combination of the reserved bit in the second identifier field and the first identifier field, wherein the reserved bit in the second identifier field is Y high-order bits in the second identifier field, and Y is less than the length of the second identifier field.