Abstract: Rice lodging resistance is affected by different concentrations of potash and silicon fertilizer. In this study, the authors used‘ ⅡYou 725’as the material and adopted a completely random design. The best concentration of potash fertilizer was 75 kg/hm2, under which the internode breaking resistance of N2, N3 and N4 increased by 4.95%, 24.15% and 35.46%, respectively, in comparing with that of control, however, the lodging index decreased by 0.86%, 14.22% and 32.06%, respectively. Further more, the best concentration of silicon fertilizer was 240 kg/hm2, the lodging index decreased by 0.06%, 18.21% and 29.20%, respectively, and the breaking resistance simultaneously increased by 5.57% , 20.29% and 17.73% , respectively. Appropriate concentration of potash or silicon fertilizer could improve the lodging resistance of rice plants, they mainly improved the breaking resistance of basal high position internodes to reduce the lodging index. As a result, application of potash or silicon fertilizer could significantly increase the grain weight and lodging resistance of rice plant.