In order to control the northern leaf blight of corn, different fungicides were used to determine the virulence in the laboratory and screen the fungicides in the field. Mycelium growth rate method was used to test and determine the field efficacy trials and laboratory toxicity. The results showed that when the mass ratio of triflumizole to iminoctadine trialbesilate was 1:7, the maximum value of the CO toxicity coefficient was 495.33, the amount of effective components was 250 g.a.i./ha, and the field control effect on northern leaf blight of corn was 84.88%. When the mass ratio of fluoxastrobin to epoxiconazole was 5:1, the maximum value of CO toxicity coefficient was 439.19,and the amount of effective components was 120 g.a.i./ha. The field control effect of fluoxastrobin on northern leaf blight of corn was 83.95%. The combination of triflumizole and iminoctadine trialbesilate, fluoxastrobin and epoxiconazole can effectively prevent the occurrence of northern leaf blight of corn.