The aim of this study is to evaluate the antifungal activity of the acetone extract of Japanese apricot fruit against plant phytopathogenic fungi. The results revealed that the acetone extract of Japanese apricot fruit could inhibit the mycelial growth of phytopathogenic fungi, including Phytophthora capsici Leonian, Fusarium solani (Mart.) Sacc., Fusarium graminearum Schwl, Botryosphaeria dothidea (Moug.) Ces. et De Not, Colletotrichum fragariae Brooks with different antifungal activities. The mycelial growth of phytopathogenic fungi was affected by the concentration of acetone extract of Japanese apricot fruit. We also evaluated the effect of the organic acids including oxalic, tartaric, malic, ascorbic, acetic, citric, maleic, fumaric and succinic acid isolated through the reverse HPLC inhibitions on the mycelial growth of Botryosphaeria dothidea (Moug.) Ces. et De Not. The results showed that the inhibitions were significant differences among the nine kinds of organic acids. In summary, we can infer that the inhibition of the extract of Japanese apricot fruit against phytopathogenic fungi is related to the kinds of organic acid presented in the fruit of Japanese apricot. .