Construction of the Luoyang-Zhanjiang Railway is applied in study.On the basis of the results of fatigue experiments of unbonded prestressed concrete beams with different mixture ratios of high-performance fly ash and the unbonded prestressed reinforcement increments calculated by the method of structural deformation,the nonlinear analysis method of fatigue damage processes of unbonded prestressed concrete beams is proposed,which takes into account the coupling action between concrete and reinforcement. The method covers stress redistribution in the fatigue damage process caused by different damaging mechanisms of constituent materials. The nonlinear damage process analysis of concrete members is achieved by means of piecewise linearity. Comparing theoretical analysis with experimental results,it is seen that the proposed method is able to well depict the whole fatigue damage process of unbonded prestressed concrete beams and predict the fatigue life more realistically