Abstract: Non-geodesic trajectory mandrel rotation and motion equations of the eye for fiber reinforced composite pressure vessels were derived by the theory of differential geometry. Practical winding parameters such as winding angle and thickness can be applied directly to stress analysis. The incremental constitutive model of laminate and piecewise linear methods were used to simulate the process of laminate damage. A new stiffness degradation model and test methods were introduced. An experimental method which determined the factor of stiffness degradation was also demonstrated . Numerical analysis for filament wound pressure vessels was finished by using this model. The results show that flexural stiffness degradation is the main factor which affects the axial displacement after the initial damage occurs.