Embodiments of the disclosure provides a BSR communication method and a terminal device. The communication method includes: determining, by a terminal device, a quantity of LCGs currently including to-be-reported buffer data; when determining that only one LCG includes to-be-reported buffer data, determining, by the terminal device, one of a plurality of BSR formats as a first target BSR format, where the plurality of BSR formats are a plurality of formats used by the terminal device to report different BSRs based on different ranges of amount of uplink data in a buffer; and sending, by the terminal device, a target BSR to an access network device using the first target BSR format, where the target BSR is used to indicate an amount of uplink data in a buffer of the LCG.