Abstract: Field experiment was carried out to investigate potassium absorption, grain yield and quality between high-oil and common corn affected by potassium application. Results indicated that the highest potassium absorption rate (HAR) of both cultivars took on a rising tendency with the augment of K application, and HAR of Tongyou 1(TY1) exceeded that of Simi 25 (SM25) when K2O was applied between 90 kg and 150 kg per hectare. In comparison with SM25, TY 1 contained much more potassium but lower grain yield at maturity. Potassium in grains of two maize varieties was mainly from K absorption by roots after flowering. Compared with SM25, both K absorptive capacity by roots after flowering and total K absorptive capacity in grain at maturity duration of TY 1 were much higher. TY1 contained more fatty acid and protein, but lower starch. Potassium application raised not only grain yield, but fatty acid, protein and their constituents. However, starch and its constituents of amylopectin, declined due to the application of potassium. The results indicated that there was some inherent relationship among fatty acid, protein, starch and grain yield.