To explore the overall structural reliability of hypersonic vehicles and its influencing factors, and ensure the structural safety of the vehicles when performing missions, a new subdomain subinterval method for analyzing the structural strength reliability of hypersonic vehicles is proposed by combining the stress-strength interference model with the interval number. Firstly, the moment of each force surface of a hypersonic vehicle under different flight conditions is analyzed. Secondly, the vehicles structure is approximated as an equivalent cantilever beam, considering the uncertainties of its moment, width and height, which are expressed as interval numbers. Then, considering the degradation of the structural strength over time, a non-probabilistic reliability analysis is carried out based on the stress-strength interference model, and a dynamic reliability model of the vehicles structure is established. Finally, a new sub-domain sub-interval method is proposed to analyze the exponential degradation characteristics of the structural strength and the impacts of the flight dynamics on the structural reliability. The simulation results show that the subdomain subinterval method is more accurate than the traditional Monte Carlo method with the same number of sampling points, which verifies the feasibility and validity of the proposed method. The reliability of the vehicle decreases gradually with the exponential degradation of the structural strength of the vehicle. In addition, the flight dynamics of the vehicle has a major impact on the structural reliability, in which the reliability of the vehicle increases with the increase of the height of flight, and decreases with the increase of the velocity as well as the angle of attack.