<p>A certain kind of composite damage warhead is mainly composed of a shaped charge warhead and a blast warhead. The shaped charge warhead is rear-mounted, and the blast warhead is placed at the front end of the shaped charge warhead. With the shock wave overpressure generated by the explosion of shaped charge warhead, the blast warhead fuze experiences extreme mechanical impact, leading to significant deformation or even failure of the fuze structure. Based on the above background, theoretical analysis of mechanical and damage behavior of fuze structure under the near-field blast load is conducted in this paper. Firstly, the theoretical analysis model of blast load bearing problem of the blast warhead fuze: the large deflection bending calculation model of inner and outer peripheral simply supported thin plate (ring plate) is established. The analytical equation of deflection distribution of the fuze cover is established. The dynamic response law of the fuze cover is obtained from the theoretical calculation point of view, and the damage failure mechanism of the fuze structure is revealed: under the near-field blast loading, the deformation characteristics of the fuze cover have reached the super advanced damage level for steel frame members. Secondly, the structural failure behavior of the blast warhead fuze under near-field blast load environment in 1:1 warhead field test is studied, and the deflection distribution curve of the fuze cover is measured, which verifies the accuracy of the theoretical analysis model. Finally, the numerical model of the composite damage warhead is established, and the elastic–plastic mechanical behavior and damage mechanism of the fuze structure under near-field blast load are analyzed through numerical simulation, which further improved the damage mechanism of the fuze structure.</p>