A sending node and a buffer status reporting method are disclosed. The method includes: classifying at least two RLC entities included in a sending node as at least one first RLC entity and one second RLC entity, where all the RLC entities are associated with a PDCP entity included in the sending node; and in a case in which a buffer of the first RLC entity includes to-be-sent data, generating a first buffer status report BSR based on a size of the to-be-sent data in the buffer of the first RLC entity, and sending the generated first BSR to a receiving node corresponding to the first RLC entity. By classification of the first RLC entity and the second RLC entity, the second RLC entity is exclusively associated with buffer status reporting of the PDCP entity.