By adopting time history method in software ANSYS, dynamic response of a liquid rocket was analyzed when it is suffered from earthquake wave EI in a launching site, and the displacement and stress of the rocket was calculated before and after it was fueled, and the safety of the liquid rocket was evaluated. The result showed that the liquid rocket swung along the acting direction of the earthquake wave both before and after it was fueled under earthquake wave EI. The higher the position of the rocket, the larger the swing. And the maximum displacement located on the top of the rocket, and the maximum stress located at the support places on the rear part. The maximum swing and maximum stress, after it was fueled, increased a lot from those before it was fueled, so the rocket has the possibility to fall down and to damage in structure.