Abstract: A simplified buried weapon bay-door-missile model was simulated with Improved Delayed Detach Eddy Simulation (IDDES) method and dynamic grid technique under the condition of different inflow Mach numbers, launching speeds and initial angular velocities. The separation trajectory varying patterns of different cases were obtained. The results show that, in subsonic flow, the Mach number has little effect on the yaw angle, while under transonic and supersonic conditions, the missile yaws to the right due to the influence of shock waves. The increase in the Mach number leads to the reduction of missile yaw and pitch angle for supersonic inflow. Raising the launching speed can make the store reach safe separation distance faster and diminish store angular variation. Increasing the initial angular velocity of the missile can reduce the pitch angle and increase the separation speed of the missile without changing the ejection force.