 This is an multi-center,single-blinded,parallel-group,dose-finding study using Remimazolam or propofol for sedation in patients undergoing diagnostic upper GI endoscopy.Subjects are randomized to different treatment groups including 4 for Remimazolam Tosilate and 1 for propofol.Lidocaine and fentanyl are permitted during a diagnostic upper GI endoscopy.Efficacy and safety profiles of Remimazolam Tosilate are to be evaluated. 