The data obtained from the crperiment of continuous liming for three years under triple cropping system of rice-rice-barley on the paddy soil derived from Quaternary red clay indieated that liming increased the yield of barley in 2-3 times, but the respond of rice to liming was not obvious. The increase of yield of barley may be mainly related to the raising of pH value of acid soil, the elimination of Al-toxicity, the improvement of growing environment and availability of P-fertilizer as well as markedly promoting of the absorption of P and K by barley. However, due to strong of rice adaptability to soil acidity, liming will depress P-absorption of rice under submerged condition. Therefore, the lime should only be applied to some upland crops as barley. It is suggested that the amount of lime far barley should be applied to neutralize soil pH at about 6.0. In any case, excesively liming is undesirable.