With the rapid development of urban underground space, flood control measures based on sandbags can no longer meet its flood control requirements. This paper studies a new mobile flood control wall based on the entrance and exit of urban underground space. The mobile flood control wall is composed of baffles, bottom plates, and struts of aluminum alloy. The working principle is as follows: increasing the friction between the bottom plate and the ground by using the vertical component of the upstream water pressure. This paper first carries out the size design, then carries on the typical analysis based on the hydrological data of a certain subway station, then uses the material mechanics method to verify the material strength, and finally verifies the model’s safety and anti-leakage ability through model tests. Through the material mechanics method, the safety factor k = 1.14 > 1, the strength meets the requirements; the impermeability is verified by the model test through the model test, and the anti-sliding stability safety factor k = 2.36 > 1.10 is calculated from the data to ensure the stability and safety of the flood control wall. By verifying the feasibility of the new mobile flood control wall, it has a positive reference significance for urban underground space flood control.