Abstract: Aiming at the shape precision control after the molding of large scale CFRP parts, which is one of the key technical problems, a modified shear-layer deformation simulation method was proposed based on the deformation prediction by shear-layer method. The modified method only needed a little test data, and the thickness of shear-layer could be determined by calculating the curvature of strain curve, then the warp deformation of CFRP parts could be predicted more exactly. A shape precision control method for large scale CFRP parts was developed based on the deformation simulating method above. This method could reduce the deformation of final parts by repeatedly compensating the deformation acquired by simulation to the initial mould surface. The comparison with the experimental data proved that the method above could effectively improve the accuracy and reduce the deformation of molding parts.