On the basis of rub-impact dynamics equation of rotor system with rub-impact fault, according with the reliability design theory and sensitivity analysis method, the reliability sensitivity analysis method of the rotor system with rub-impact was extensively discussed by applying the random perturbation theory, Kronecker algebra, the fourth moment technology and matrix calculus theory. A numerical method for reliability sensitivity design of rotor system with rubimpact was presented. The variation regularities for reliability sensitivity of random parameters statistics characteristic were obtained and the effects of random parameters statistics characteristic on reliability of the rotor system were studied. The presented method provided the theoretic basis for the reliability design of the rotor system with rub-impact. A numerical example demonstrates that the result of presented method is accord with the qualitative analysis, the proposed method is efficient and accurate.