In the structural dynamic optimization procedure, many repeated analyses are conducted to evaluate dynamic performance of successively modified structural designs. It is noted that, the reduction of degrees of freedom is more important for computational effort in dynamic problems than in static problems. This paper focuses on the reanalysis for structural dynamic problem in the framework of combined approximations (CA) method. A new procedure for structural dynamic reanalysis is developed based on iteration and inverse iteration method with frequency-shift in mode superposition method, and linear combination acceleration is also used to reduce the high computational cost of structural reanalysis. Frequency-shift factor is calculated first, and then combined approximations method corrected by the given factor allows calculating higher modes accurately. After higher modes are obtained, mode expansion and dynamic response can be described accurately. Numerical examples are presented to demonstrate the accuracy of the proposed method. Excellent results can be obtained when large modifications are made.