The invention relates to an antifungal protein separated and purified from bacillus subtilis J18, a protein product, a preparation method and an application. A strain serial number of the bacillus subtilis J18 is CGMCC No.3665, and a strain name is the bacillus substilis J18. The preparation method of the protein product comprises the following steps of: mixing the J18 antifungal protein with 1 percent of acetic acid to form a chitosan solution with a pH value of 6.0, compositing the chitosan solution to form a film coating reagent which has the concentration of 0.05mg/mL and is used for soaking a fruit, and also coating a mixture which is formed by mixing the J18 antifungal protein solution with an oxidized starch solution on a preservative paper to prepare an antifungal preservative paper used for wrapping the fruit. The antifungal protein has remarkable control effect to fruit and crop diseases and particularly black spot diseases of pears after picking and is an antagonistic strain with broad spectrum and high efficiency.