Cantilever rotor is the key component part of mechanical equipment. Based on the failure mode of dynamic response of the cantilever rotor, the ensitivity factors which affect structure reliability, such as load, size of structure, properties of materials, are analyzed. The utmost equations of the cantilever rotor in both static and dynamic states are built. Each equation is linearized at the average point by Taylor Expansion scheme. The reliability of structure is calculated by employing the theory of the primary second moment. The reliability results of considering and ignoring the inertial force respectively are compared mutually and analyzed. Then, an effective reliability analysis method for cantilever rotor is established.