Abstract: To analyze the effect on dispersion stability of non-circular cross-section projectile, using Fluent program, the centroid trajectory and rotation angle during projectile dispersion were studied numerically. The results show that the final rotation angel of centroid radial direction decreases as negative exponential function, when initial dispersion velocity increases. With different attack angle of projectile, centroid radial and axial rotation angle decreases when the initial axial deflection angle increases. And the reduce rate of centroid radial deflection angle is slower relatively. An addition of angle attack increases radial deflection but reduces of axial deflection. The effect of trajectory attack angel and radial rotation is not obvious on centroid axial rotation.