Abstract: The influence mechanism of the missile-head shape, launch angle and ejection velocity on the missile trans-phase stability was studied to provide the experimental and theoretical support for the design of diversified ballistic trans-phase weapon/aircraft. Carried out the missile water-to-air trans-phase experiments and numerical simulations, obtained the missile trans-phase deflection angle variation and trajectory through processing the transient images, established the high-precision air/water trans-phase numerical model, and the function mechanism of the missile head, launch velocity, launch angle on the load-sustaining distributions on the missile surface and the trans-phase stability as passing through the air/water interface was revealed. The research results indicated that the calculation error of the missile air/water trans-phase numerical model is < 5%; for the same missile model, the water-to-air trans-phase stability increases as the launch velocity, angle increase; under the same launch conditions, the water-to-air trans-phase stability of different missile-head shapes: round head > 90° conical head > 120° conical head > flat head; the better symmetric water film shape on the missile surface and the smaller water film area variation amid trans-phase process will reduce the missile trans-phase radial load amplitude, which improves the trans-phase stability.