The invention relates to a compound synergistic bactericidal composition for preventing and curing main diseases of tomatoes and pear trees, and an application of the composition. The active components of the pesticide composition comprises adepidyntm and an active component B, wherein the active component B comprises one selected from a group consisting of strobilurin fungicides, an ergosterol synthesis inhibitor, substituted aniline fungicides and bacillus subtilis BAB-1. The pesticide composition provided by the invention is applied in preventing and curing main diseases of tomatoes and pear trees such as grey mold, early blight, leaf mold, grey leaf spot, Venturia inaequalis, ring spot, black spot and the like, has a good fast-acting property and persistence, has a novel action mechanism, has many sites, can effectively delay the generation and development of drug resistance of pathogenic bacteria, and not only has protection effects against diseases, but also has good curing effects. The compound synergistic composition has less pesticide usage amount, and effectively reduces pollution on fruits and environment by drugs.