This research mainly dealt with the purification and stability of recombinant peptide IYPR(Ile-Tyr-Pro-Arg)expressed in E.coli.The inclusion bodies were washed,separated from the cells by ultrasound assisted extraction.After purification by affinity chromatography,recombinant protein was cleaved with enterokinase and trypsin.The purified IYPR was collected from gel filtration.The information had also been realized regarding the activity of purified IYPR under different conditions including temperature,pH and gastrointestinal proteases.The results showed that the recombinant protein was recovered with a high purity of about 90 % by affinity chromatography.The series peptide of IYPR and the 6×His tag were successfully isolated by dialysis.Peptide IYPR was obtained by cleavage of the recombinant protein with trypsin.When the sample was heated at 90 ℃ for 1 h,the activity of IYPR was reduced to 98 % of the original.Incubation in aqueous solutions(from pH 2 to 10) for 5 h didn't change the activity of IYPR.When the peptide was digested by pepsin,its activity was increased by 13.0 %.The data obtained provided a good reference for further development of peptide IYPR into an effective antihypertensive agent for prevention and treatment of hypertension.