Abstract: Random meterial properties,geometrical shapes,forces and displacement boundary condition of an aeroengine are directly introduced into functional variational formulations and a unified random variational principle and the probabilistic finite element method with the small parameter perturbation method are provided.Based on second-order perturbation technique,the formulations for the random stresses and the reliability of the aeroengine′s structures are derived.According to analysis the characteristics of these random parameters,the simple methods for analyzing the aeroengine structural reliabilty are obtained.At last,the reliability of a rotating disk of the aeroengine is analyzed with a simple numerical example.