Abstract: Two maize genotypes, high phosphorous efficiency genotype (ND 181) and low phosphorous efficiency genotype (ND 197) were used to study the effects of inoculating AM fungi to the corn southern leaf bligh. The result shows that there is a significantly negative relationship between corn southern leaf bligh diease level and the shoot phosphorous concentration at the seedling stage of maize. This means that the improvement of phosphorous nutrition could lower the disease of corn southern leaf bligh. When the applications of P are at 20 and 50 mg/kg (under P deficiencies), the disease incidences are highest. For the low P efficiency genotype, ND 197, the inoculating of AM fungi could improve the P nutrition, and the disease index of corn southern leaf bligh is lower. But for the high P efficiency genotype, ND 181, the inoculating of AM fungi could not improve the P nutrition, and the disease index of corn southern leaf bligh is not changed significantly. Through the above results, we could conclude that the inoculating of AM fungi could improve the resistance of maize to the disease of corn southern leaf bligh and the P nutrition.