Abstract: Based on an analysis of the filament winding pattern and filament undulation , a new method for calculating the elastic modulus of filament winding composites is presented. A representative filament winding pattern wasselected and the pattern was divided into a laminate field and a filament undulation field to calculate their elastic moduli respectively. For the laminate field , the elastic modulus was calculated according to the classical laminate theoryand , for filament undulation field , the elastic modulus was calculated according to the meso-scale filament undulation situation. The whole elastic modulus of the pattern was obtained through combining the two-field elastic moduliwith the area ratios of each field to the whole pattern. The calculated elastic moduli are in good agreement with thoseof carbon/ epoxy filament winding composite tubes under tensile loading , which shows that the presented method isvaluable for calculating the elastic modulus of filament winding composites.