It was found that the deactivation of Horse Radish Peroxidase(HRP) by gamma-ray was very severe at room temperature, but at low temperature(-78℃) it's deactivation could be controlled effectively.,Radiation entrapping immobilization of HRP at low temperature was performed, but the leakage of immobilized HRP from gel made this method undesired.,In this work, a new immobilization method of HRP vis pre-irradiation polymerization of acrylamide was developed. In this method, sample solution of acrylamide and proper ratio of crosslinking ,agent, were being irradiated with bubbling oxygen continuously and then, take the sample out of radiation field, put some unirradiated HRP into the sample which was still not polymerized bubbling high pure nitrogen for about 15 minutes. Finally the sample was polymerized and at the same time the HRP would be entrapped in it.,Some entrapping conditions were investigated. About 60% of HRP can be entrapped and the leakage of HRP gel was somewhat improved.