Hespintor is an unknown function protein that was got from hepatoblastoma cell lines HepG2 by suppression subtractive hybridization technique (SSH), sequence analysis showed that the protein is a new member of secretory type of Kazal type serine protease inhibitor (Serpin) family, and has high homology with esophageal cancer related gene 2 (ECRG2). The coding sequence of Hespintor's Kazal domain was subcloned into prokaryotic expression vector pET-40b(+), then transformed into Rosetta (DE3). A recombinant protein about 42 kDa in the form of inclusion body was optimization expressed by inducing with 0.25 mmol/L IPTG, 30 degrees C for 5 h. and its specificity was confirmed via Western blotting. The recombinant protein was purified by metal chelate affinity chromatography (MCAC) and anion-exchange chromatography. The preliminary experimental result showed that the recombinant protein can inhibit trysin hydrolysis activity specifically. The result clearly demonstrated that Hespintor, as a novel member of Serpin, would be valuable in developing anti-tumor agents.