On the basis of the realistic demand for lightweight impact-resistant materials in weaponry, a Ti575 alloy, which possesses high strength-plasticity-impact toughness matching, was taken as the object of this research. Ti575 alloys with trimodal and widmanstätten microstructures were prepared through heat treatment, and dynamic mechanical property tests were carried out at a strain rate of 3 500 s-1 via the Hopkinson pressure bar technique combined with microstructural evolution analysis by scanning electron microscopy observations. This study aims to reveal the deformation behavior and response mechanisms of Ti575 alloys through these tests, thereby providing guidance for subsequent research. The results indicate that the high strain rate deformation behavior of the Ti575 alloy with these two different microstructures can be divided into four stages: the elastic stage, strain hardening stage, stable softening stage, and unstable softening stage. The results of the dynamic compression tests reveal that the trimodal microstructure results in greater impact absorption energy than does the widmanstätten microstructure (trimodal microstructure: 228 J/cm3; widmanstätten microstructure: 200 J/cm3), demonstrating better dynamic mechanical properties of the trimodal structure than that of the widmanstätten microstructure. Additionally, both microstructures display characteristics of adiabatic shear failure during high strain rate deformation. The characteristics of fewer and wider adiabatic shear bands in the trimodal microstructure suggest that it has lower sensitivity to adiabatic shear than the widmanstätten microstructure does, resulting in superior dynamic mechanical properties in the trimodal microstructure relative to the widmanstätten microstructure. Subsequent studies on the fracture mechanisms show that the fracture surfaces of the two microstructures of Ti575 alloys deformed at high strain rates consist of ductile dimple regions and smooth areas. Moreover, high-magnification SEM observations indicate that both microstructures primarily demonstrate ductile fracture characteristics, along with typical signs of shear fracture.