Abstract: Objective To evaluate the clinical effect of maxillary sinus floor elevation with bone extrusion and simultaneous implant in patients with the distance between the maxillary sinus and the alveolar ridge <3 mm in the posterior maxillary sinus area. Methods From January 2012 to January 2015, 265 posterior partially edentulous patients with the distance between the maxillary sinus and the alveolar ridge<3 mm were chosen to receive the lateral sinus lift accompanying bone extrusion and Simultaneous Placement of Implants. After 12 to 60 months of follow-up, the healing effect, the cumulative survival rate of the implant, the bone height of the implant, and the stability of the implant were evaluated. Results A total of 210 implants were implanted in 125 patients. The cumulative retention of the implants in 5 years was 99.5%. In the 1 years after completion of the superstructure repair, the bone height around the implants was absorbed (0.85 + 0.25) mm, and the bone resorption in 1 years after operation was less than 0.2 mm per year. The ISQ value of the retreated implants every half year after the operation was more than 70. During the follow-up period, the implant exercised a good masticatory function. Conclusion The maxillary sinus floor elevation with bone extrusion and simultaneous implant in patients with the distance between the maxillary sinus and the alveolar ridge <3 mm in the posterior maxillary sinus area have a definite clinical effect, can effectively reduce the patient’s treatment time.