A method and an apparatus for measuring channel quality in a MIMO system is provided. The method includes measuring a first SINR based on an assumption that a first detector is used, using a channel estimation value of a reception signal with respect to each of a plurality of space layers, and a second SINR for each of the plurality of space layers corresponding to a case where the plurality of space layers exist independently using the channel estimation value of the reception signal; determining a Log Likelihood Ratio of reception data based on an assumption that a second detector is used, with respect to each of the plurality of space layers; and generating channel quality information based on an assumption that the second detector is used, based on the first SINR and the second SINR with respect to each of the plurality of space layers, and the LLR.