Abstract: The gene of RipB was amplified by PCR from the genome of Mycobacterium tuberculosis(MTB) and was constructed into the expression plasmid pET 21a. After transformation the recombinant RipB expression vector into E.coli BL21 (DE3) competent cell, recombinant RipB was induced expression in E. coli by IPTG. SDS PAGE analysis showed that recombinant RipB was about 40% of total bacterial protein, mainly expressed as inclusion bodies at 37 ℃, but mainly soluble at 15 ℃. Recombinant RipB was one step purified by Ni NTA affinity chromatography and obviously accelerated the proliferation of micrococcus luteus at 100 pmol/L.