the present invention provides a method and apparatus reporting a channel quality indicator of a communication system , including : detecting a first measurement reflecting a first communication quality of the communication system ; providing a series of thresholds and mapping functions , each mapping functions in association with a bin defined by two adjacent thresholds , so the first measurement is mapped to the channel quality indicator by the mapping function in association with the bin which matches the first measurement ; and updating at least one of the thresholds according to a second measurement which reflects a second communication quality of the communication system .