The off-plane separation technology of rigid body projectiles is one of the key technologies for the development of a new generation of aircraft. The off-plane safety analysis of rigid body projectiles in different ejection conditions remains to be investigated. At present, the research on the effect of the angle of attack and the ejection angle of the cylindrical projectile on the off-plane safety of cylindrical projectile is still insufficient and requires further research. The off-plane safety performance of the cylindrical projectile is investigated in this paper. The ejection separation trajectory and off-plane safety are simulated by solving the unsteady Navier-Stokes equations and the k-ω Shear Stress Transport turbulence model coupled with the six-degree-of-freedom motion equation. The effect of the ejection angle and the aircraft angle of attack on the off-plane safety of the cylindrical projectile is evaluated by demonstrating distributional properties. The results obtained show that the cylindrical projectile rotate after leaving the aircraft, and the trajectory of the cylindrical projectile during separation is parabolic. The separation trajectory tends to be a straight line as the angle of attack of the aircraft increases. The off-plane safety can be improved by reducing the angle of attack of the aircraft. Furthermore, the off-plane safety of cylindrical projectile improves as the ejection angle increases.