Abstract: The enzyme β-galactosidase was entrapped in a pressure-sensitive poly(N-iso-propylacrylamide)gel.By using o-nitrophenol β-D-galactopyranoside(ONPG)and lactose respectively as the substrate,experiments on the immobilized enzymic reaction were carried out.Operations under constant pressure and pressure cycling conditions were compared with regard to the increase in conversion rate with reaction time.Remarkable improvement of the immobilized enzymic reaction was achieved during pressure cycling operations,owing to the enhancement of mass transfer inside the gel beads.