Objective To establish diagnostic standards of confocal laser endomiroscopy (CLE) in pathological classifications of gastric cancer and evaluate the diagnostic value of CLE in vivo. Methods The confocal images of 36 patients, who were diagnosed as gastric cancer with confirmation of pathology, were collected and analyzed to establish diagnostic standards of CLE for pathological classifications of gastric cancer. The sensitivity, specificity and accuracy of CLE were determined with reference to histopathologic findiugs retrospectively. Results According to changes of glandular architecture and microvessels under CLE, gastric cancers were divided into differentiated and undifferentiated type. The sensitivity, specificity and accuracy of CLE in diagnosing differentiated carcinoma were 85.7%, 92. 3% and 90. 5%, respectively, which were 85.7%, 92. 3% and 90. 5%, respectively, in undifferentiated carcinoma. Conclusion CLE is a new tool to make pathological classifications of gastric cancer during routine endoscopic examination procedure, which correlates well with histopathologic fingdings.