A simulation method of line heat forming of hull fabrication is proposed in this paper. The calculation methods of local contraction values for two kinds of complex curved Sail-Shaped plates are introduced. The mathematical models of the relation between the maximum retraction length and the parameters acting on the plates are cstablished by theorems of stepression and mathematical statistics. The Validity of the methods is presented on the basis of experimental data. The optimum design method of preessing technical parameters is also discussed