To improve the health status evaluation accuracy of inertial navigation systems，we developed a new characteristic reliability calculation method based on wave distance. It aims to address problems such as a lack of fault data，uncertain knowledge，and complex environmental disturbances. The degree of interference was measured using the wave distance from the historical data. Subsequently，a belief rule-based expert system considering the characteristic reliability was constructed. Health status was evaluated using a combination of unreliable data and uncertain expert knowledge. A case study was conducted based on observation data from the gyroscopes and accelerometers of an inertial navigation system. The accuracy of the developed method is 0.283 8. Compared with the traditional belief rule-based model，its accuracy is higher by 15.28%.