Objective To discuss the standard of endoscopic diagnosis of duodenal white spot syndrome and to test its accuracy by pathological diagnosis standard. Methods A total of 6,995 patients undergoing gastroscopy were detailedly examined through gastrofiberscope or electrogastroscope and endoscopic diagnosis were made by the standard of endoscopic diagnosis of duodenal white spot syndrome. Then, pathological examination was done to test and verify the accuracy of the standard of endoscopic diagnosis. Results There were 533 patients suffering from duodenal white spot pathological changes, accounting for 7.62%. And duodenal mucositis was confirmed by pathological findings in all 90 cases of the patients undergone their biopsy at the same time. Conclusions The appropriate standard of endoscopic diagnosis can improve the detection rate of duodenal white spot syndrome and there is a high coincidence rate between endoscopic diagnosis and pathological diagnosis.