Abstract: Based on the hypothesis of rectangle and biconvex section shape of the yarn,and different collocation between the inner warp and outer warp,thickness,section shape of the same structure being considered especially,a model for predicting the elastic property of 2.5-D woven composites was developed.To verify the elastic model,62 samples of 2.5-D woven composites with 6 various structures were selected and the elastic properties were measured.Experiment results are in good agreement with the outcomes of the model.Further,it is shown that the difference between the inner warp and outer warp can't be ignored in predicting the elastic property of 2.5-D woven composites.