Abstract: In order to determine the control efficacy, field trials were carried of with kresoxim-methyl 30% suspension concentrate(SC), kresoxim-methyl 60% water dispersible granule(WDG) and Trichoderma harzianum 3 billion cfu/g wettable powder(WP) to control powdery mildew of cucumber. The results showed that, all fungicides have excellent control efficacy, and two successive fungicide applications enhances the control efficacy significantly. the control efficacy of kresoxim-methyl 30% SC 1000 times liquid was 70.34% on 7 days after the 1st spraying, and the treatments of Trichoderma harzianum 3 billion cfu/g WP have a certain rapid action, meanwhile, slightly better than kresoxim-methyl 60% WDG on control efficacy, the control efficacy of 250 times liquid reached to 79.98%. Most control efficacy were higher than 85% in 7 days after the 2nd spraying, two of these, kresoxim-methyl 60% WDG 2000 times liquid and Trichoderma harzianum 3 billion cfu/g WP 180 times liquid, up to 96.37% and 97.10% respectively. Therefore, it was recommend that alternate use of the Trichoderma harzianum and others in the field application.