A three-dimensional finite element model with different stitching densities was established,which was based on the stitched carbon fabric satin reinforced composites,and the elastic modulus of the composites was predicted.The stitched composite specimens prepared by RTM process were used to test and verify the validity of the finite element method.The result shows that the in-plane elastic modulus of the composites decrease with the increase of the density,with the maximum magnitude of the reduction of about 44%,The Poisson"s ratio of the composites has no significant change.The experimental result is consistent with the regularity of finite element prediction.