Abstract: The aim of this study was to analyze the characteristics of ChiⅠ (chitinase classⅠ) in tobacco by using bioinformatics methods and tools. This research laid foundations for further research of ChiⅠ on disease of tobacco. Bioinformatic methods were used to predict and analyze the ChiⅠ (chitinase classⅠ) from NCBI of Nicotiana tabacum, Arabidopsis thaliana, Oryza sativa and Phaseolus vulgaris in sequence characteristics and phylogenetic relationships. The results demonstrated that the molecular weight of the ChiⅠ with signal peptide from the four plants were 28-37 kDa. The ChiⅠ had a glycoside hydrolase family 19 domain and N-terminal chitin binding domain, which was highly conservative among chitinases from several different plant species. The phylogenetic relationship of Nt-ChiA, Nt-ChiB and Nt-ChiC, and the relationship between ChiⅠ from Nicotiana tabacum and one of ChiⅠ from Arabidopsis thaliana and Phaseolus vulgaris was closer than that from Oryza sativa. The result implied the properties of ChiⅠ in tobacco were almost the same as that of other plants. This study provided the basis for further research on tobacco disease resistance proteins.