By analyzing the strength and the stability after the topological optimization design of the open-hole topology of the solid floor in the inner pressure-resistant tank, it is found that the solid floor opened near the inner keel is better for the inner pressure-resistant tank with a circumferential range of 162°. It has little effect on its own stability for the opening of the solid floor, but the stress of the MIMES will change. The stability of the liquid tank structure will be slightly reduced when the hole is opened. So, the structure requires strengthening when designing the liquid tank structure in the later stage.