Base on Finite Element Analysis (FEA) and fatigue theory, the hub is used as an example of the fatigue life calculation and study. The fatigue strength include the casting unit load calculation, the fatigue load spectrum and the material S-N curve were studied. The study hotspot of the hub body was used of the principal stress method, combined with the casting material S-N curve fitting to calculate the value of hot damage, and used of the Fesafe software to calculate the hub surface fatigue damage. Fatigue life of the hub was rapidly evaluated. This calculation method for the evaluation of fatigue life of wind turbine hub can be reference by other casting.