The invention discloses an application of cinnamate compounds in prevention and control of fungal diseases of crops. The cinnamate compounds have one of chemical structures represented by formulas shown in the description. The cinnamate compounds have strong antibacterial activity, have a wide antibacterial spectrum on pathogenic fungi of crops, are safe to crops in order to avoid phytotoxicity, and have better or equivalent field pesticide effect than a control compound 3, 4-dimethoxycinnamate when used to prevent and control fungal diseases of crops, such as powdery mildew, damping-off, rot,gummy stem blight, anthracnose, white rot, leaf blight, late blight, gray mold, phytophthora, Fusarium Patch, early blight, blight, full rot, pythium rot, dry rot, ring rot, banded sclerotial blightand Sclerotinia sclerotiorum.