The agnH gene was cloned and expressed in the nicotinedegrading Agrobacterium tumefaciens SCUEC1 strain,and the conditions of expressing and purifying AgnH protein were optimized.The full length agnH gene (585 bp) was amplified by PCR,and the recombinant plasmid pET28a(+)agnH was constructed and transformed into E. coli BL21(DE3) strain for heterologous expression.The effect of different IPTG concentration,induction temperature and induction time on the expression of recombinant plasmid pET28a(+)agnHwas studied.The recombinant protein was eluted with different concentrations of imidazole eluant,and the expressed protein was detected with SDS-PAGE.The results showed that the agnH gene was cloned and the recombinant plasmid pET28a(+)agnH was constructed.The expression of AgnH protein was higher under the conditions of IPTG concentration of 0.4 mmol/L,induction temperature of 25℃ and induction time of 25 h.A higher concentration of AgnH protein was obtained by elution with a 250 mmol/L imidazole eluant.