Abstract: In order to study the disturbance flow field characteristics of the submunition during the dispersal, the multi-cabin submunition was selected as the calculation model, based on the unstructured hybrid grid Reynolds average Navier-Stokes equation solver HUNS3D developed by the research group, combined with the unstructured overset grid technology. The six-degree-of-freedom rigid body kinematics equation was coupled. The six-degree-of-freedom rigid body motion equation was solved by using the improved fourth-order Adams predictor-correction method. Using the typical external object separation under transonic speed as a verification example, the simulation results are highly fitted with the experimental results, and the accuracy of the solver is verified. Then the numerical simulation of the two calculation states of the degree of freedom of locking the projectile and releasing the projectile was carried out. The simulation results show that there is a strong coupling between the submunition and the projectile due to the shock interference. After releasing the freedom of the projectile, the aerodynamic parameters of the submunition have changed greatly.