A method of adaptive channel quality calculation by a User Equipment in a mobile communication system is provided. The method includes calculating a filtering coefficient indicating a length of a filtering interval according to a Carrier to Interference-plus-Noise Ratio (CINR) variation rate of each subband per unit time, and calculating a channel quality of each subband filtered according to the filtering coefficient. An environment having a large scheduling gain according to the difference in the channel quality of each subband and an environment not having as large a scheduling gain are thereby discriminated from each other in measurement of the channel quality of each subband, to apply different Infinite Impulse Response (IIR) filtering coefficient values a used for calculation of CINR of each subband.