In order to solve the problem that it is difficult to realize the automatic production mode for the production of polymer bonded explosive (PBX) explosive by using large explosion-proof vertical kneader, 5 and 40 L capacity kneader models were established, and the parameters under the same mixing time were analyzed by numerical simulation. Compared with 40 L kneader, the maximum temperature, shear rate, shear stress, maximum pressure, difference of aluminum powder uniformity, safety distance of shock wave and sympathetic detonation of 5 L kneader at 4s are reduced by 0.768%, 49.6%, 51.5%, 47.9%, 0.0619, 75% and 64.6% respectively, and the hazard area is reduced by 50%. The results show that the continuous and automatic production of cast PBX explosive can be realized by replacing one large kneader with several small kneaders.