Abstract: The deformation of composite parts during curing process is one of the key technique problems. Analytical calculation model and finite element simulation model were proposed to predict the curing deformation of composite parts by introducing a shear layer between the tool and composite part. The shear modulus of the shear layer was used to measure the interaction between the tool and composite part during curing process. The value of shear modulus was obtained by comparing with experimental data. Based on the proposed curing deformation model, the results were compared with experimental results in reference. Results show that the proposed model has good reliability. Meanwhile, a three dimensional finite element simulation model, which took part anisotropy of materials, chemical shrinkage and interaction between the tool and composite part in molding process into account, was also established for L-shaped composite part. Simulation results show that by introducing tool interaction, we could accurately predict curing deformations for L-shaped part.