Abstract: Objective To explore the diagnostic and diagnostic accuracy of endoscopic ultrasonography (EUS) in the diagnosis and localization of submucosal masses in digestive tract and the safety and efficacy of minimally invasive treatment under the guidance of endoscopy. Methods A total of 291 patients underwent gastrointestinal miniprobe sonography from May,2015 to April,2017 in Bengbu Medical College.According to the results,the endoscopic surgical procedures,such as endoscopic submucosal tunnel resection(STER),endoscopic resection(EFR),endoscopic mucosal dissection(ESD),and so on,were selected.The pathological results were recorded and compared with the results of ultrasonography.The success rate of treatment,the presence of laparoscopic or laparotomy,the postoperative complication and its treatment were observed.The effectiveness of endoscopic ultrasonography and endoscopic treatment were evaluated.The postoperative regular endoscopic follow-up was carried out. Results The accuracy of miniprobe sonography diagnosis was 70.43%,and the accuracy of localization was 87.90%.There were 6 cases of intraoperative perforation,1 case of pulsatile bleeding,and 1 case of mucosal laceration in gastric cardia,which were all closed with titanium clip.One case of pulsatile bleeding during EFR surgery was stopped by hot spoon forceps.Four cases of subcutaneous emphysema during STER disappeared after conservative treatment.Four cases of intraoperative active bleeding,with fail hemostasis or unclear vision,were converted to laparotomy surgery.One case of tumor could not be dissected during STER surgery and be sampled for a biopsy,and the examination showed it was squamous cell carcinoma,which was suspected to be tumor metastasis on the basis of history.Other tumors were successfully removed,without significant postoperative complications.The endoscopic resection rate for complete tumor was 97.45%. Conclusion Gastrointestinal miniprobe sonography has a high degree of qualitative and localized diagnostic accuracy for digestive tract submucosal masses.In particular,the diagnosis of localization is helpful for safe selection of endoscopic minimally invasive treatment.