Abstract: Class I chitinase plays an important part inallergy of lots of plant food. This allergen has a relationship with and responsible for latex-fruit syndrome. Chitinase was harmful to human health on some conditions. In our study chitinase was isolated from citrus fruits. Compared with fruits of orange and pummelo, the relative expression level of chitinase in satsuma fruits was significant higher than the others.Cross-reactivity of allergen was also found, for the reason that high similarity of the amino acid sequences with many other varieties. The secondary structure with DNAStar was obtained. Meanwhile the corresponding amino acid sequences of antigen index > 0, surface probability > 1, hydrophilicity > 0, flexible regions > 0 were all obtained.When the sequences of amino acid were corresponding to these conditions, as well as that the secondary structures were β-turn and irregular corners, the chance of B-cell epitopes was higher.Based on the comprehensive prediction analysis, we could infer that B-cell epitopes of chitinase had the high probability in regions of 62~69, 96~100, 126~133, 145~149, 155~159, 169~172, 179~182, 189~190, 256~262.These results could provide theoretical basements for antibody preparation and many other researches.