Objective:To evaluate the effects of crown lengthening surgery by apically repositioned flap for the treatment of the teeth with inadequate width of attached gingiva. Methods:17 teeth with inadequate width of attached gingiva were included. The gingiva flap was repositioned apically. The distance between gingival margin to the root surface was recorded, the width of attached gingiva and other indicators were compared before and 6 months after surgery. Results:Edge of the defects the 17 teeth was below gingiva margin before surgery, root surface was exposed to the coronal gingival margin 6 months after surgery in 16 of the 17 cases (94. 11%). Api-cally displacement distance of the gingival margin was (3. 88 ± 0. 49) mm. The width of attached gingiva before and 6 months after sur-gery was (2.35 ±0.61) mm and (2.65 ±0.49) mm respectively(P>0.05). Conclusion: Crown lengthening with apically reposi-tioned flap surgery can effectively expose the root surface and create conditions for restoration of dental defects for teeth with inadequate attached gingiva, and can prevent over removal of the keratinized gingiva.