As a model of serine hydrolase, the condensation polymers of salicylic acid, formaldehyde and methyl amine, n-propyl amine, n-hexyl amine or n-lauryl amine were prepared by polycondensation catalyzed by sulfuric acid. It was confirmed by potentiometric titration and infrared spectrum that the polymers containing tertiary amino group possess the structure which resembles the internal salt of amino acid in weak basic and weak acidic solution:The catalytic reaction of the above polymers for hydrolysis of active ester,p-nitrophenyl acetate(PNPA),was studied.It was found kinetically that the most efficient catalytic effect of polymer was composed of two salicylic acid groups and one tertiary amino group in the polymer chain.The rates of hydrolysis of PNPA increase with increasing of pH values and length of the alkyl groups in the side chain of the polymers and the effect of the conformation of the polymer containing tertiary amino group in the buffer solution on the catalytic activity was also investigated.Hydrolysis of PNPA catalyzed by the polymer made of salicylic acid,formaldehyde and n-lauryl amine follows the simple Michaelis-Menten type mechanism.The kinetics parameters were determined as:Km6.7×10-5M and Vmax2.07×10-7M·min-1.