The invention discloses a microbicide composition and an application thereof. The microbicide composition comprises an active ingredient and a chelating agent, wherein the active ingredient comprises Zhongshengmycin and chitooligosaccharides, and the weight ratio of the Zhongshengmycin to the chitooligosaccharides to the chelating agent is 1: (0.1 to 15): (5 to 30). The chelating agent comprises at least one of edetic acid, sodium metaphosphate, sodium tripolyphosphate, ammonium citrate, potassium sodium tartrate and aminotriacetic acid. When wettable powder, water-dispersible granules and soluble liquid agents prepared from the microbicide composition disclosed by the invention and microbicides of other compositions and dosage forms are used in a tumble-blend manner, flocculation, precipitation and the like are not caused, and the pesticide effect of tumble-blend use is remarkably improved.