Disclosed are a compound represented by formula I, a preparation method therefor, and a use thereof. See the specification for the definition of each substituent group in formula I. The preparation method comprises the following step: performing, in the presence of a catalyst in an organic solution, a condensation reaction on a compound represented by formula IV and a compound represented by formula V to obtain the compound represented by formula I. The preparation method is simple, and the resulting compound represented by formula I is applicable to prevention of a number of plant diseases caused by pathogenic fungi, such as oomycetes, basidiomycetes, ascomycetes, and imperfect fungi, and can effectively prevent powdery mildew on wheat, maize rust, and watermelon anthracnose in particular. Using a low concentration of the compound achieves a good prevention effect. Moreover, a part of the compound represented by formula I has excellent insecticidal activity and acaricidal activity and is capable of protecting crops from a number of pests and mites. Therefore, the compound can be used as a germicide or a pesticide in agriculture or other fields.
