Abstract: Chitinase is an important plant-pathogen related protein. Preliminary research in the laboratory found that the relative expression level of tea plant chitinase CsC7 significantly increased when different resistant tea varieties were inoculated with the pathogenic fungus of tea cake disease（Exobasidium vexans）. Based on this, the homologous sequence of tea plant chitinase CsC7 gene was cloned from the ’Meizhan’ material and preliminary research on the function of CsC7 protein through bioinformatics analysis was conducted. Furthermore, CsC7 was transferred into Pichia pastoris X-33 expression express proteins through vector construction, and the antibacterial activity of purified yeast heterologous expressed protein CsC7 against seven fungi, including Mucor fragilis, Inonotus obliquus, Fusarium oxysporum, Alternaria alternata, Botrytis cinerea, Fusarium chlamydosporum, and Pleospora herbarum, was analyzed by plate inhibition assay. The results showed that purified yeast heterologous expressed protein CsC7 had significant inhibitory activities against Mucor fragilis, Inonotus obliquus, Fusarium chlamydosporum, Fusarium oxysporum, and Botrytis cinerea, with inhibition rates of 27.07%, 21.90%, 28.45%, 39.21% and 32.23%, respectively, while there was no significant inhibition effect on Alternaria alternata and Pleospora herbarum.