Abstract: The coding region of the tea cystatin was amplified by RT-PCR and cloned into expression vector pET-32a(+). The tea cystatin expression plasmid pET-TC was thus obtained. Expression of the plasmid in Escherichia coli BL21trxB(DE3) resulted in the production of a special fusion protein(ca.31.8kDa)． With the inducing time increasing, the amount of fusion protein also increased, the highest content amounted to 35.4% of gross proteins. Different temperature( 15 ℃, 25 ℃, 30 ℃and 37 ℃) and different density of IPTG from 0.5 mmol/L to 5 mmol/L all could induce expression of fusion protein, and most of them was soluble. Furthermore, the results of in vitro enzymatic reaction indicated that the special fusion protein had biological-activity and exhibited inhibitory activity toward papain.