Objective: To investigate the effect of PDCA cycle on improving Oral hygiene of adolescent patients during the fixed orthodontic treatment. Methods: A total of 100 adolescent patients with fixed appliances were randomly divided into two groups, the experimental group, and the control group, with 50 adolescent patients in each group. The PDCA cycle was used to the experimental group for the management of oral hygiene, including making plan of improving oral hygiene, formulating strategy based on questions and investigations, checking oral hygiene status, getting stage summary and continuous improvement. The control group was given oral health education with multimedia software. Plaque index and Bleeding index were evaluated for the oral hygiene condition before treatment, 6 months and 12 months after Orthodontic treatment in both groups. Results: Before treatment, there was no significant difference between the experimental group and the control group in PLI and BI. At the beginning of treatment, PDCA cycle was applied in the experimental group. After 6 months and 12 months of treatment, PLI and BI of the experimental group significantly decreased while that of the control group showed no significant change. After repeated application of PDCA cycle, the proportion of patients with PLI ≤1 and BI ≤1 increased to 82% and 92% respectively (P<0.05). Conclusion: PDCA is effective for the oral hygiene of adolescent patients.