Objective：The aim of this study is to clarify ERS and the expression level of WFS1 in IUGR newborn rats，further exploring the molecular basis related to T2DM，which may provide a new therapy for preventing IUGR from leading to T2DM. Methods：The pregnant rats in the IUGR group were fed 50% calorie restriction from gestational day 14 until term. Immunohistochemistry，RT-PCR，transmission electron microscope and western blot were applied. Results：①The expressions of WFS1 and GRP78 in the pancreas and islets of IUGR rats were increased（P < 0.05，n=10）. ② Electron microscope showed that the endoplasmic reticulums in the pancreas of newborn IUGR rats were swollen and fused. ③Glucose-regulated protein 78（GRP78/Bip）and CHOP were significantly elevated in the pancreas and islets of IUGR. Conclusion：This study demonstrated that WFS1 might play roles in maintaining islet structure and function in IUGR rats，maybe partly via UPR.