To investigate the effect of mold inner flow channel structure on the forming process of nitroguanidine gun propellant, the mold inner flow channel model of 11/7 nitroguanidine gun propellant was established. The numerical simulation of nine schemes of different combinations of shrinkage angle as 30°, 45° and 60° and forming section length as 25, 30 mm and 45 mm was performed. The effect of shrinkage angle and forming section length on the shear rate, pressure and velocity distribution in the extrusion process were analyzed. Results show that the shrinkage angle has similar effects on the interfaces of different contraction sections and forming section and nearing-outlet etc.sections, and it shows that the shear rate of the propellant dough near the center of mold needle and the wall surface is higher than that of the surrounding pare. The sectional pressure distribution is uniform and the flow velocity distribution of the dough has the characteristics of large middle parts and small two sides. The length of forming section has a great influence on the shear rate distribution during the extrusion process of dough. The smaller the length of the forming section, the more likely the sudden change of shear rate, which may lead to the unsteady flow. At the same time, it can be determined that the optimal inner flow channel parameter scheme is the shrinkage angle of 45° and the forming section length of 30 mm.