To express and purify the histidinekinase VicK from Streptococcus mutans and to detect its protein activity. The VicK gene was synthesized and constructed into the prokaryotic expression vector pET28a by DNA recombination techniques. After the construction was confirmed correctly by enzymatic digestion and sequence analysis, the products of expression which was induced by IPTG were analyzed by SDS-PAGE. The activity of purified target protein was detected by Kinase-Glo^® Luminescent Kinase Assays. Vick cDNA was cloned into pET28a plasmid successfully. Using 0.3mmol/L IPTG at 18! for 15 h, the soluble target protein was expressed efficiently ,and was purified by Ni affinity column .The target protein of 2mg/ml has does-dependent kinase activity of hydrolyzing ATP in vitro. The successful expression and purification of vick protein which has does-dependent kinase activity provided basis for further research of inhibitors screening targeting Vick protein of streptococcus mutans.