The role of exogenous salicylic acid (SA) in regulating an antioxidative defense response of sweet cherry ( Prunus avium L. cv. Hongdeng) fruit inoculated with Penicillium expansum was investigated by immunodetection of carbonylated proteins. After inoculation with P. expansum, carbonylated proteins accumulated to a lesser extent in SA-treated fruit than in control fruit, ranging from molecular mass 29–45 kDa. Higher activities of catalase (CAT), glutathione peroxidase (GPX), chitinase and β-1,3-glucanase were observed in SA-treated fruit. Similarly, the expressions of CAT, GPX and β-1,3-glucanase genes were also stimulated by SA treatment. Moreover, 2 mM SA did not inhibit P. expansum growth in vitro. These results indicate that SA activated antioxidant defense responses of sweet cherry fruit, which may play a role in the resistance against P. expansum.