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.