A method and a device for generating and reporting an Overload Indicator (OI) report. A controller jointly carries out conversion of a number system on a binary number used by an OI value in each Physical Resource Block (PRB) group indicated by a set grouping tag value. The controller converts a value generated by the conversion of the number system into a new binary number, and joints the new binary number in each PRB to generate the OI report. The controller carries out the above operations according to all the set grouping tag values, and compares the number of bits occupied by the OI report corresponding to each grouping tag value to select a PRB grouping mode corresponding to the OI report occupying the least number of bits as the OI format of the controller.