A method for reporting a buffer size index, comprising: presetting a first table which is a buffer size index table used by a Long Term Evolution, LTE, system, and presetting a second table which is a buffer size index table by increasing a maximum buffer size value to B max-A and increasing a minimum buffer size value to B min-A based on the first table, or by increasing the maximum buffer size value to B max-A, and increasing a number of the buffer size index to N LTE-A; choosing, by a User Equipment, UE, in reporting a Buffer State Report, BSR, to inquire on the preset first table or second table for the buffer size index; and sending, by the UE, the inquired buffer size index to a base station in the BSR; wherein the maximum buffer size value is increased to B max-A and the minimum buffer size value is increased to B min-A based on the first table; and the method further comprises: after increasing the maximum buffer size value to B max-A and increasing the minimum buffer size value to B min-A based on the first table, expanding the number of the buffer size indexes in the first table to k max, wherein k max is a minimum value meeting B k-max ≥ B max-A, B k-max is an upper limit value in a buffer size range which is indicated by the buffer size index in the case that the buffer size index in the expanded first table is k max; intercepting the buffer size indexes meeting that B k is between B min- A and B k-max in the expanded first table as the second table, wherein the number of the buffer size indexes in the second table is N LTE-A, which is set to be less than or equal to the buffer size index N used by the LTE system. presetting a first table which is a buffer size index table used by a Long Term Evolution, LTE, system, and presetting a second table which is a buffer size index table by increasing a maximum buffer size value to B max-A and increasing a minimum buffer size value to B min-A based on the first table, or by increasing the maximum buffer size value to B max-A, and increasing a number of the buffer size index to N LTE-A; choosing, by a User Equipment, UE, in reporting a Buffer State Report, BSR, to inquire on the preset first table or second table for the buffer size index; and sending, by the UE, the inquired buffer size index to a base station in the BSR; wherein the maximum buffer size value is increased to B max-A and the minimum buffer size value is increased to B min-A based on the first table; and the method further comprises: after increasing the maximum buffer size value to B max-A and increasing the minimum buffer size value to B min-A based on the first table, expanding the number of the buffer size indexes in the first table to k max, wherein k max is a minimum value meeting B k-max ≥ B max-A, B k-max is an upper limit value in a buffer size range which is indicated by the buffer size index in the case that the buffer size index in the expanded first table is k max; intercepting the buffer size indexes meeting that B k is between B min- A and B k-max in the expanded first table as the second table, wherein the number of the buffer size indexes in the second table is N LTE-A, which is set to be less than or equal to the buffer size index N used by the LTE system. after increasing the maximum buffer size value to B max-A and increasing the minimum buffer size value to B min-A based on the first table, expanding the number of the buffer size indexes in the first table to k max, wherein k max is a minimum value meeting B k-max ≥ B max-A, B k-max is an upper limit value in a buffer size range which is indicated by the buffer size index in the case that the buffer size index in the expanded first table is k max; intercepting the buffer size indexes meeting that B k is between B min- A and B k-max in the expanded first table as the second table, wherein the number of the buffer size indexes in the second table is N LTE-A, which is set to be less than or equal to the buffer size index N used by the LTE system.