The present invention provides a reporting method of terminal Buffer State Report (BSR), obtaining method for obtaining the BSR from a base station, and corresponding terminal, base station, communication system. The terminal includes: buffer state index table; at least one extended buffer state index table; index table selector, selecting one of the index table from the said buffer state index table and the said at least one extended buffer state index table; index determination device, determining the index which is corresponding to the data quantity in the said index table according to the data quantity in the terminal buffer; index sender, sending the said index to the base station.