Abstract: The chitinase from endophytic bacterium KKWB-5 was expressed in Escherichia coli to identify the antagonistic activity of the chitinase against Fusarium oxysporum f.sp cubense race 4 (Foc 4). The chitinase gene amplified by PCR was inserted into the expression vector pET22b, and the recombinant plasmid was transformed into E. coli BL21 (DE3). The recombinant strain was induced with IPTG, and SDS-PAGE was used to analyze the expression of objective protein in E. coli. Then the recombinant protein was purified and renatured, and the hydrolysis activity and the antagonistic activity against Foc 4 of the renatured protein were determined. The results of SDS-PAGE analysis showed that the recombinant objective protein was abundantly expressed in the form of inclusion body in E. coli. Recombinant protein with high purity was purified from inclusion body protein by denaturated Ni2+ affinity chromatography. The yield of objective protein reached 293 mg per 1 L culture. The yields of refolding protein using dialysis renaturation which was 84.6 %, was higher than that using dilution renaturation. The activities tests indicated that the renatured protein was hydrolytic of chitin, and was antagonistic against Foc 4, but the antagonistic activity was weak. In conclusion, the chitinase from endophytic bacterium KKWB-5 was effectively expressed in E. coli, and the renatured chitinase was resistant to Foc 4 to some extent. Thus the chitinase made some contributions to the antagonistic activity against Foc 4 of endophytic bacterium KKWB-5.