Abstract: The effects of the aqueous solutipn of sodium hydroxide and nitrilotripropionamide CN(CH2CH2CONH2)33 as additive agent on radiation polymerization of the aerylamide (AM) by the action of 60Co γ-rays are investigated. Ordinarily, at content of the sodium hydroxide in the range of 0.34-0.72% and absorption doses at (1.1-3.3)×104 rads in polymerization, polyacrylamide (PAM) with a good solubility in water and a molecular weight about 5×106 can be obtained. The nitrilotripropionamide crystal could be obtained before polymerization in the AM system only when ammonia-water is being added. By adding the nitrilotripropionamide as additive agent in the range of 1.5-2.5% in the polymerization system, a PAM product is obtained with a molecular weight above 3×106 and becomes well soluble in water. If the amount of nitrilotripropionamide added is less than before mentioned, cross-linking insoluble polymer appears. The molecular weight decreases obviously if the nitrilotripropionamide content is above 3%.In our experimental conditions, the nitrilotripropionamide crystal was not observed in the AM system in the presence of sodium hydroxide, while nuclear magnetic resonance spectrum showed that the content of the nitrilotripropionamide is about 0.06% in the system containing 0.53% sodium hydroxide and 67% AM at the room temperature.The cross-linking mechanism of polymerization chain due to hydrogen free radical H during AM radiation polymerization is discussed.