Abstract: The integral seismic analysis of reactor head package (RHP) and control rod drive mechanism (CRDM) was performed with simplified three-dimensional finite element model which reflected the collision effects among seismic support plates and between seismic ring and seismic support plates, and the tension-compression nonlinear characteristic of seismic tie rods. Through the nonlinear analysis, the seismic loads necessary for component stress analysis can be derived for each part of RHP and CRDM. Meanwhile, the time-history data of acceleration can be provided for CRDM seismic qualification test.