Recombinant expression vector of the Streptococcus agalactiae ATCC51487 gene was established by using PCR amplification,double digestion of EcoRⅠand XhoⅠ,and resistance screening,etc. Effects of induction temperature,concentration and time on the expression products were examined. The protein was purified by affinity chromatography and ion exchange chromatography,and the activity of SrtA was determined using energy transfer resonance. The results showed that after the srtAΔN82-pGEX- 6p - 1 vector was transformed into BL21 (DE3),a large amount of soluble protein were obtained by inducing at 1 mmol/L IPTG at 37℃ for 6 h. The purity of SrtA was higher than 85%. Moreover,the purified SrtA could significantly increase the fluorescence intensity when co-incubated with the substrate,indicating that the recombinant SrtA had good biological activity.