On the basis of basical equations of structural dynamics, a wind turbine blade was treated as a free suspended beam which was entirely fixed on the root. Then the physical and mathematical models of wind turbine blades were built. Blades of a 15 kW wind turbine were Modeled in the AutoCAD. With the aid of finite element analysis (FEA) software ALGOR, the model of blades were analyzed on the vibration modes which were under irrotating and different rotational speeds. Natural frequencies and mode shapes were calculated. And then frequency response for the baldes of wind turbine were analyzed, and the vibration magnitude and stress distribution of the blade were obtained when acted by the exciting force.