Superabsorbent polyacrylic acid/montmorillonite composite (SAPC) with high water absorption capacity prepared using 9 MeV electron beam irradiation is presented in this paper, which is different from others in material composition and preparation method[1-3].Acrylic acid (AA) aqueous solution (20%-30%) neutralized with sodium hydroxide, solution of montmorillonite and additives were put together and mixed. Nitrogen gas was introduced into the system to replace the oxygen dissolved in the solution. The solution was irradiated with the E-beam. The gel formed by the irradiatior was dried and characterized. Water absorption capacity (WAC) was measured with gravimetric method.It was proved that an optimun dose range for crosslinking of the composite and formation of the water-absorption gel was 10-20 kGy. Further increase of the irradiation dose would desease WAC of the product after the crosslinking structure formed.If the concentration of a polymerization system is too low, no gel formation would be observed in the system.However, the reaction heat generated during the polymerization increases with an increasing concentration. If the heat cannot be moved in time, the system would be heated to very high temperature, and even an explosive polymerization may occur and the process would be out of control. Theoretical calculation and experimental results show that the highest concentration of AA cannot exceed 30 %. On the other hand, a high concentration polymerization system is energy-saving for the drying process.At the same irradiation condition, decreasing the AA/montmorillonite ratio could increase WAC of the SAPC. This is because, perhaps, that the presence of montmorillonite decreased the polymerization speed and the crosslinking density. But, too low a ratio could not form enough crosslinking points, and the gel portion would be so low that the product would be partly dissolved in the solution.Methylene N, N-bisacrylamide (0.02 %--0.06 %) was used in the reaction system to reduced the irradiation dose.Changing the degree of neutralization (DN) of AA will change the WAC. However, concerning the product property, it should be controlled at neutral.AA/montmorillonite polymerizes faster in nitrogen gas than that in the air, because the oxygen in the solution can combine with the radicals formed by the irradiation. Meanwhile, with a high dose rate irradiation, the influence of irradiation atmosphere become smaller.The products characterized with XRD showed that the AA intercalated into the laminar of the montmorillonite.In conclusions, SAPC with high water absorption capacity (1500gram water/gram SAPC) was prepared by proper control of the polymerization conditions of the irradiation dose (1-20 kGy), concentration of the irradiation system (2 %-30 %), additives (0.02 %-0.04 %), degree of neutralization of AA and irradiation atmosphere, etc