In order to understand the structural reliability of the solid rocket warhead in transport, the frequency domain method is used to evaluate the fatigue damage degree. The simplified kinetic model of the rocket launcher was built and the base excitation PSD (power spectrum density) of the charge was calculated by the transfer function and road load PSD; the finite element model of the charge was established and dynamic responses were solved by mode superposition methods; the fatigue damage degree was evaluated by Steinberg′s 3-σ Law. Results show that the random vibration of the warhead charge causes the dynamic stress, and the inner face of the top hole is the danger place with the stress peak value of 4.86 MPa. When the loading time reaches 250 h the damage degree is 1.12, which reveals that the warhead charge has been broken. The road roughness load can bring about the fatigue damage of the warhead charge, which has negative impacts on the structural reliability.