Abstract: Field experiments are carried out to study the effects of organic fertilizer potassium and chemical fertilizer potassium combination on the yield, quality and potassium nutrient utilization efficiencies of leafy vegetables in a vegetable planting base of Chongqing. The results indicated that yields of lettuce and cabbage increased significantly (11.6%- 17.4% and 10.9%- 15.4% , respectively) under the combination treatment compared with that of no potassium treatment, in the two experiments, the highest yield was achieved under the MH +KL treatment. The yield of lettuce and cabbage under the combination treatment was higher than that of conventional potassium treatment, but the increase was not significant. The combination treatment could increase Vc content, decrease amino acid and soluble sugar content of lettuce, but it had little effect on cabbage. Nitrate contents in lettuce leaves, stems and cabbage were decreased by 4.8%-5.4%, 4.9%-11.1% and 15.5%-30.0%, respectively, and the MH +KL treatment had the best result. The combination treatment significantly increased potassium uptake and potassium utilization efficiency of lettuce and cabbage, and those under the MH+KL treatment were the highest, and the treatment was the optimal for leafy vegetable production.