Based on the N - S equation and the k-ε model, this article uses the dynamic grid technology to finish the numerical simulation of projectile-barrel coupling for muzzle flow field of the double-barreled aircraft gun during asynchronous firing under different incoming Mach numbers and different firing intervals. The influence law of muzzle flow field on projectile motion is studied. The results show that when there is supersonic incoming flow, the radial force on the projectile will increase with the increase of incoming Mach number. At the same time, the larger the Mach number, the earlier the radial force of the projectile will be affected. Under the same inflow Mach number, the radial force on the projectile when the double-barreled aircraft gun is fired asynchronously is significantly lower than that when fired synchronously. The larger the firing interval, the smaller the radial force on the projectile.