The nonlinear analytical model of an external prestressed concrete wind tower was developed based on fiber beamcolumn element. Four damage states were defined based on the results obtained from pushover analysis. Twenty recorded ground motions were selected as the basis of incremental dynamic analysis. The peak ground acceleration and the horizontal displacement ratio were chosen as the intensity measure and the structural seismic demand parameter, respectively. Nonlinear incremental dynamic analysis was then performed and the probabilistic model of seismic demand was built through regression analysis based on lognormal assumptions. Subsequently, the fragility analyses were produced. The seismic fragility of the tower was evaluated, proving that the wind tower meets the requirements of 7degree seismic fortification intensity. For 8degree earthquakes, however, the probabilities of serious or complete damage significantly increase, according to the proposed analyses.