In order to study the factors affecting the conformity of the type and size of the variableburning rate propellant and provide a reference to the actual operation for setting the appropriate parameter,threedimensional flows of variableburning rate propellant solution in the screw were simulated using the polyflow software under different operating conditions. Simulation results show that the volume flow rate of outside layer is directly proportional to the screw velocity. When the screw velocity is different,the high frequency fluctuation values of the volume flow rate are 0. 017%-0. 036%. The fluctuation values of the volume flow rate are directly proportional to the fluctuation values of the screw velocity. The volume flow rate of the outside layer is directly proportional to the entrance pressure. When the entrance pressure is different,the high frequency fluctuation values of the volume flow rate are 0. 024%-0. 025%. When the screw velocity is higher,the fluctuation values of the volume flow rate rapidly increase with the increasing of the fluctuation values of the screw velocity. When the entrance pressure is higher,the fluctuation values of the volume flow rate rapidly increase with the increasing of the fluctuation value of entrance pressure. The fluctuation values of the screw velocity affect the volume flow rate of variableburning rate propellant more largely than the fluctuation values of the entrance pressure.