Abstract: Based on the theory of Fourier series，a model for predicting the stiffness of filament wound composite was provided according to the characteristic of micro-structure of filament-wound composite. In this model，the stiffness of representative volume element (RVE) was treated as a stiffness field; the function of this field was described by 2D Fourier series expansion and the expressions were deduced. The result of the example shows that the model can predict the macro-stiffness of filament-wound composite, also can reflect the effect of internal micro-structure of filament wound composite on the stiffness characteristic of filament wound composite.