The compressive true stress-true strain curves of TC4 alloy with different strain rates at room temperature were investigated by the INSTRON test machine and split Hopkinson pressure bar (SHPB) device. Johnson-Cook (JC) constitutive model of TC4 alloy was established by fitting the experimentally obtained stress-strain curves. Based on the constitutive model, the impact compression experiment of TC4 alloy at high strain rate was simulated by ABAQUS. The correctness of the parameters for the constitutive model was verified by comparing the experimental results with the simulation data. In order to achieve the goal of lightweight of the mortar, a new lightweight titanium alloy mortar base plate was designed. The finite element model of the mortar base plate under impact load was established considering the strain rate effect of TC4 alloy. The strength and stiffness of the base plate were analyzed, and the variation law of the stress and displacement of the base plate was obtained. The research results of this paper provide a reference for lightweight design and development of the base plate and other equipment structures.