To investigate the feasibility of two-stage crestal approach sinus elevation in severe atrophic maxilla. A total of 25 patients (male: 13 cases,female: 12 cases) who attended Department of Implant Center, Stomatological Hospital, Southern Medical University from May 2016 to May 2018 were included in this study. The age of the patients was 32-49 years old. The inclusion criteria were: single or multiple tooth loss in posterior maxilla with residual bone height ranged from 1.5 to 3.0 mm and vertical bone width≥6 mm, no pathological changes or septum were detected in the sinus. The elevated sides were divided into three groups according to different buccal-palatal sinus width (SW): wide (16 case, SW>15 mm), normal (12 case, 12 mm≤SW≤15 mm), narrow (5 case, SW<12 mm). Finally, 23 patients with 33 implants were placed by the two-stage crestal approach for sinus elevation. Six months after implant placement, final restorations were delivered. Implant survival rate, implant stability quotient (ISQ), immediate vertical bone height (VBH) after surgeries, changes of sinus elevation height (cSEH), marginal bone loss (MBL) at 1 year follow-up were examined. Twenty-three patients were finally included in the study, including 12 males and 11 females, aged (41.2±7.6) years old. All implants healed uneventfully. ISQ (wide: 50.81±2.69; normal: 60.58±2.54; narrow: 63.12±3.58), immediate VBH after 1st surgery [wide: (7.99±1.13) mm; normal: (8.95±0.81) mm; narrow: (9.18±0.90) mm] and 2nd surgery [wide: (11.46±0.88) mm; normal: (12.77±0.49) mm; narrow: (12.57±0.55) mm], cSEH six months after 1st [wide: (3.87±0.43) mm; normal: (2.01±0.65) mm; narrow: (1.49±0.33) mm] and 2nd [wide: (1.16±0.29) mm; normal: (1.04±0.33) mm ; narrow: (0.97±0.41) mm] surgery, MBL [wide: (0.91±0.05) mm; normal: (0.79±0.10) mm; narrow: (0.74±0.07) mm] were significantly different among three groups (0.05). In all the three groups, cSEH was barely detected at 1-year follow-up (0.05). Two-stage crestal approach for sinus elevation might be an alternative protocol in severe atrophic posterior maxilla, especially in cases with narrow and normal buccal-palatal width. There is an urgent need for long time follow-up and more clinical cases.