Recombinant chymosin expressed in Pichia pastoris(GS115 / pPICZαA-chyomsin) was partially puri-fied and characterized.Recombinant chymosin was obtained by fractional precipitation with ammonia sulfate,followed by the chromatography of DEAE-52 and Sephadex G-75.After purification the specific activity of the enzyme prepara-tion increased from 672 U/mg to 3 865 U/mg.The milk clotting activity of the purified enzyme was stable between pH 3.0 ～ 7.0 with maximum activity at pH 5.0.The activity of the purified enzyme was with increasing CaCl2 concentra-tion up to 0.02 mol/L.However,a gradual increased reduction of the activity was observed by increasing NaCl con-centration between 1% ～ 20%.Ni + and Cu2 + had an inhibitory effect on the recombinant chymosin.Fe2 +,Fe3 +,Mn2 +,Mg2 + had a stimulating effect on the recombinant chymosin.