Embodiments of the present invention provide a method and device for triggering Buffer State Reporting (BSR), which relate to the wireless communication field and are used to solve the problem of lacking a triggering mechanism for Device-to-Device communication Padding Buffer State Reporting (D2D Padding BSR) in the prior art. In an embodiment of the present invention, a user equipment determines the size of padding resources when organizing a Device-to-Network-link Media Access Control layer Protocol Data Unit (D2N MAC PDU), and decides whether to trigger the D2D Padding BSR or not according to the size of the padding resources and the priority of the Padding Buffer State Reporting Media Access Control layer Control Element carrying the Device-to-Device communication (D2D Padding BSR MAC CE), thereby the D2D Padding BSR triggering mechanism is achieved.