Immobilized trypsin in mesoporous silica foams was used to catalyze dipeptide synthesis in hydrophilic organic solvent instead of soluble form. The area surface of nano support was measured. The catalytic activity, coupled yield and kinetic characterization of immobilized trypsin were examined. Bz-Arg-OEt was chosen as the acyl donor with Lys-OH as the nucleophile. The trypsin-catalyzed synthesis condition was optimized, such as catalytic temperature, pH, reaction time, physical properties and content of organic solvents, together with the added enzyme amount. The immobilized trypsin showed 112.8% of residual activity with 91.9% of coupled yield, and the kinetic parameters exhibited accessibility for transmission. The product yield of 5.8% was reached at the optimum conditions for enzymatic synthesis of dipeptide: 800 mg of wet immobilized trypsin (200 mg/g support) was used in Tris-HCl buffer (0.1 mol/L, pH 8.0) containing 80% (v/v) ethanol solvents for 6 h of reaction time at 35 ℃ . This attempt of mmobilized strategy for trypsin in nanopores renders the possibility of wide application of inorganic nano-sized support in catalytic synthesis process, which can avoid usage of large amounts of organic solvents in washing steps by chemical methods and reduce the tedious purification process of its soluble form.