A method for transmitting data, comprising: determining, by a terminal device, a reporting format of a buffer status report, BSR, of one Logical Channel Group, LCG, when the terminal device has only the one LCG with data to be transmitted, wherein the reporting format is a first format or a second format, the first format being different from the second format; and reporting, by the terminal device, the BSR of the one LCG according to the determined reporting format of the BSR of the one LCG; wherein before determining the reporting format of the BSR of the one LCG, the method further comprises: receiving, by the terminal device, indication information sent by a network device, wherein the indication information is indicative that the terminal device reports the BSR of the one LCG according to the first format when the terminal device has only the one LCG with data to be transmitted, or the indication information is indicative that the terminal device reports the BSR of the one LCG according to the second format when the terminal device has only the one LCG with data to be transmitted; wherein the method is characterized in that determining the reporting format of the BSR of the one LCG comprises: determining, by the terminal device, the reporting format of the BSR of the one LCG according to the indication information; wherein the indication information comprises a first service type, and the first service type is indicative that the terminal device reports the BSR of the one LCG according to the first format when a service type corresponding to the one LCG is the first service type, and the terminal device reports the BSR of the one LCG according to the second format when the service type corresponding to the one LCG is not the first service type. determining, by a terminal device, a reporting format of a buffer status report, BSR, of one Logical Channel Group, LCG, when the terminal device has only the one LCG with data to be transmitted, wherein the reporting format is a first format or a second format, the first format being different from the second format; and reporting, by the terminal device, the BSR of the one LCG according to the determined reporting format of the BSR of the one LCG; wherein before determining the reporting format of the BSR of the one LCG, the method further comprises: receiving, by the terminal device, indication information sent by a network device, wherein the indication information is indicative that the terminal device reports the BSR of the one LCG according to the first format when the terminal device has only the one LCG with data to be transmitted, or the indication information is indicative that the terminal device reports the BSR of the one LCG according to the second format when the terminal device has only the one LCG with data to be transmitted; wherein the method is characterized in that determining the reporting format of the BSR of the one LCG comprises: determining, by the terminal device, the reporting format of the BSR of the one LCG according to the indication information; wherein the indication information comprises a first service type, and the first service type is indicative that the terminal device reports the BSR of the one LCG according to the first format when a service type corresponding to the one LCG is the first service type, and the terminal device reports the BSR of the one LCG according to the second format when the service type corresponding to the one LCG is not the first service type. receiving, by the terminal device, indication information sent by a network device, wherein the indication information is indicative that the terminal device reports the BSR of the one LCG according to the first format when the terminal device has only the one LCG with data to be transmitted, or the indication information is indicative that the terminal device reports the BSR of the one LCG according to the second format when the terminal device has only the one LCG with data to be transmitted; wherein the method is characterized in that determining the reporting format of the BSR of the one LCG comprises: determining, by the terminal device, the reporting format of the BSR of the one LCG according to the indication information; wherein the indication information comprises a first service type, and the first service type is indicative that the terminal device reports the BSR of the one LCG according to the first format when a service type corresponding to the one LCG is the first service type, and the terminal device reports the BSR of the one LCG according to the second format when the service type corresponding to the one LCG is not the first service type.