Disclosed is a substituted cyanoaniline compound or a salt thereof, wherein the compound has a structure represented by General Formula I. The compound of General Formula I has broad-spectrum fungicidal activity in the field of agriculture and effectively prevents against a variety of pathogens such as cucumber downy mildew, wheat powdery mildew, maize rust disease, rice blast and cucumber gray mold. In particular, even at a low dose, the compound effectively prevents and treats rice blast, cucumber gray mold, maize rust disease and cucumber downy mildew. Moreover, the raw materials for preparing the compounds are widely available and the synthesis method therefor is simple and convenient.