Objective To evaluate the value of endoscopic ultrasonography （EUS） combined with conventional endoscopy for prediction of invasion depth of early gastric cancer and its therapeutic decision-making. Methods Patients with biopsy-proven gastric cancer underwent EUS and conventional endoscopy from July 2011 to January 2018 in Ningbo No.2 Hospital. A total of 129 patients with early gastric cancer confirmed by postoperative pathology were enrolled in the study. The sensitivity， specificity， positive predictive value， negative predictive value， consistency （the value of Kappa） and area under receiver operating characteristic curve （AUC） of EUS， conventional endoscopy and combination of two methods to assess the accuracy of tumor infiltration depth were analyzed. The accuracy of therapeutic decision-making based on the EUS， conventional endoscopy and combination of two methods were assessed. Results In intramucosal cancer， the sensitivity， specificity， positive predictive value， negative predictive value， the value of Kappa and AUC of EUS were 75.00％， 82.22％， 88.73％， 63.79％， 0.536 and 0.797， respectively， and for conventional endoscopy， these statistical values were 61.9％， 93.33％， 94.55％， 56.76％， 0.481， and 0.801， respectively. For the combination of two methods， these statistical values were 85.71％， 82.22％， 90.00％， 75.51％， 0.666 and 0.850， respectively. In submucosal cancer， the sensitivity， specificity， positive predictive value， negative predictive value， the value of Kappa and AUC of EUS were 51.11％， 86.91％， 67.65％， 76.84％， 0.403 and 0.697， respectively， and for conventional endoscopy， these statistical values were 57.78％， 73.81％， 54.17％， 76.54％， 0.311 and 0.678， respectively. For the combination of two methods， these statistical values were 71.11％， 90.48％， 80.00％， 85.39％， 0.632 and 0.817， respectively. The accuracies of therapeutic decision-making of EUS， conventional endoscopy and the combination of two methods were 83.72％， 68.22％ and 92.25％， respectively. Conclusion Patients who are diagnosed as intramucosal caner by conventional endoscopy should not be recommended to undergo EUS. For those whose invasion depth is unclear， or diagnosed as submucosal cancer or deeper by conventional endoscopy， EUS should be performed for reassessment. The combination of two methods can improve the accuracy of distinguishing intramucosal and submucosal caners and therapeutic decision-making. Trial registration Chinese Clinical Trial Registry， ChiCTR-DDT-13003299.