Abstract: The effects of the initial concentration of hydrazine, the concentration of nitric acid, the amount of catalyst (S/V), the temperature and the β irradiation on the decomposition rate of hydrazine catalyzed by Pt were studied. The results show that the decomposition rate of hydrazine increases with the increase of initial concentration of hydrazine, the temperature, the amount of Pt catalyst and the decrease of the concentration of nitric acid; the decomposition rate of hydrazine under Pt catalyst is significantly increased with the introduction of β irradiation. The apparent rate constant of N₂H₄ decomposition is 19.3 times higher than that of Pt alone, 1.35 times higher than that of β alone, and the decomposition rate depends on the irradiation position of β. The kinetic rate equation of hydrazine decomposition in Ptcatalyzed nitric acid system is described as follows: -dc(N₂H⁺₅)/dt=kc(N₂H⁺₅)c^-0.39(HNO₃), and at the temperature of 296 K, the rate constant(k) is (5.90±0.35)×10^-3mol/(L·min), and the activation energy(Ea) is (333.3±2.9) J/mol.