Abstract: The selection of shrinkage is one of the critical factors in successful design for large casting polyurethane elastomer(CPUE) mold.Based on experiments, the influence of process parameters on shrinkage of large CPUE products was systematically studied.The structural model of the products and the neutral network based on BP were estabilished.Through the learning of experimental data,the neutral network model could be used to predict the shrinkage of large CPUE by taking the process parameters as input and product shinkage as output.The comparison of prediction results and experiment data indicated that the shrinkage of CPUE at different process parameters could be predicted.Thus the number of mold repairing and production cost could be reduced.