Using the matrix perturbation theory, it is an ideal method to apply the modal superposition method to the dynamic equation of general damping matrix to solve dynamic response of structure. However, when the frequency of the system is close to the natural frequency of the system, the damping matrix as the perturbation matrix make the solution singular and lead to the solution failure or large error, because the dynamic equation under modal coordinates is the undamped equation. In order to solve this problem, th consider to retain some damping in the dynamic equation of the modal coordinateshe damping is decomposed and substituted into the vibration equationobtain the different order perturbation equation, and the perturbation equation is transformed to modal coordinatesthe nonsingular perturbation method. Finally, the firstorder and secondorder perturbation solutions are obtained by numerical examples, which are compared with the exact solutions. The accuracy is improved, basically tend to be the exact solution, which verifies the accuracy and effectiveness of the method.