Objective To express and purify the envelope ( E) protein of Japanese encephalitis virus (JEV) in soluble form.Methods Various prokaryotic expression vectors , host strains and induction conditions including time and temperatures were screened to obtain an optimum prokaryotic expression system for JEV E protein in soluble form .The expressed protein was purified by using nickel column chromatography and gel filtration chromatography .Results The soluble JEV E protein , accounting for 23% of the totally bacteria soluble protein was effectively expressed by using the recombinant plasmid PBCX -E406 at low tem-perature.The purity of the expressed protein reached up to 85%after the purification by using nickel column and gel filtration chromatography .Conclusion Soluble JEV E protein was successfully expressed and puri-fied in a simple and efficient way .It would provide a useful tool for further investigation on JEV infection , attenuation mechanism of JE live vaccine strain SA 14-14-2 and the quality control of JE vaccine .It can also be used for the development of diagnosis assay for JEV .