The invention discloses a germicidal composition prepared from triflumizole and SYP-Z048, prepared from effective components and a pesticide adjuvant; the effective components are the triflumizole and the SYP-Z048, the weight ratio of the triflumizole to the SYP-Z048 is 1 : 10 - 10 : 1, and the weight percentage of the weight sum of the triflumizole and the SYP-Z048 in the composition is 1 to 70 percent. According to actual application requirements, the germicidal composition can be prepared into one of emulsion in water, microemulsion, a suspending agent, wettable powder and a water dispersible granule, and is used for preventing and treating grape powdery mildew; compared with a single agent, the prevention and treatment effect of the germicidal composition is obviously improved, the usage dosage of a pesticide is lowered, the pesticide use frequency is reduced, the pesticide cost is lowered, and the adverse effect of the pesticide to ecological environment is reduced.