A wind turbine located in Yunnan is taken as an example in this paper. By using the analytical method and the finite element method, the modal analysis of wind turbine tower is carried out, then the structural dynamic behavior is obtained. Based on the comparison of the results from different calculation methods, the rigidity and the resonance of tower induced by wind wheel rotation are studied. The research shows that, the finite element model is simplified, while the results of this method are rich; the transient resonance inevitably appears for two times in the starting process for the flexible wind tower which has the structure of symmetry basically; while in the normal operation stage, the wind wheel would not induce the resonance for flexible tower. The research provides a theoretical basis for the design of wind turbine tower.