Purpose: To investigate the effect of using mucoperiosteal-bone flap split technique when width of alveolar bone ridge is insufficient. Methods: The width of alveolar bone ridge is 3-5mm. Patients underwent mucoperiosteal-bone flap splitting. A horizontal incision was made at the top of the alveolar ridge, and two vertical incisions at the mesio-distal alveolar bone, and the whole layer of the periosteum was cut through. The cortical bone was cut using an ultrasonic scalpel. As a result, the mucoperiosteal-bone flap was split. Results: The narrow alveolar bone was succeeded to be split. And gingiva was not recessionary, split bone was not necrotic after operation. Conclusion: Mucoperiosteal-bone flap split technique can solve the problem of insufficient bone width.