Abstract： Objective:To investigate the clinical effect of disk-up sinus reamer (DSR) in maxillary sinus floor elevation with maxillary sinus septum.Methods:Twenty-four patients were included between January 2019 to January 2020 in Department of Oral Implantology, The Affiliated Hospital of Qingdao University. There were 10 males and 14 females with the age of (39.3± 11.7) years (range 22-56 years). Pre-operative(T0) cone-beam CT (CBCT) was taken for measurement and analysis. All patients were divided into group E (easy situations, septum located anterior to the zygo-matic process), group M (moderate situations, septum located posterior to the zygomatic process) and group D (difficult situations, sagittally oriented septum). The maxillary sinus floor was grafted through the crestal approach by DSR and implants were placed simultaneously. Permanent repair was performed 6-8 months after operation. All patients underwent CBCT before surgery, after surgery immediately (T1), 6 months after surgery(T2), 1 year after surgery(T3), 2 year after surgery(T4). The residual bone height (RBH) and the vertical bone height (VBH) were analyzed. The mucosal perforation rate, implant survival rate were counted.Results:All the 24 patients completed the maxillary sinus lift surgery successfully and 24 implants were placed simultaneously. All patients had no headache, dizziness. The mucosal perforation rate was 0 (0/24). The survival rate of implants during the healing period was 100% (24/24). The RBH was (5.26±1.90) mm pre-operation, the VBH T1, VBH T2, VBH T3 and VBH T4 were (11.82±1.09), (10.98±0.52), (10.66±0.44) and (10.40±0.33) mm, respectively. The differences between the groups by pairing test were statistically significant ( F=187.70, P<0.001), expect VBH T3 and VBH T4 ( P=0.071). Bone resorption and remodeling mainly occurred 1 year after surgery. One patient developed peri-implantitis 18 months after surgery. Conclusions:With the RBH of implant site>2 mm and existence of maxillary sinus septum, using DSR for sinus floor elevation has a high success rate. It can obtain enough bone height and complete the simultaneous implantation to form a good osseointegration. The DSR is simple, safe and controllable, and can shorten the operation time.