Warpage is a common defect resulted from uneven thermal shrinkage during injection molding process. In this paper, the authors investigated finite element method to predict the warpage of injection moldings with thin shell theory. In order to improve calculating accuracy, discrete Kirchhoff element combined membrane element with rotational degrees of freedom was used to build finite element model. The results predicted with this model were compared with experimental data. The results showed that this finite element model was effective to increase the prediction accuracy of the warpage because of bring transfer matrices to improve the element accuracy.