Abstract: Objective: To explore the effect of oral irrigator as an auxiliary method on improving periodontal health in adult orthodontic treatment with fixed appliance. Methods: Fifty volunteers between 22 and 28 were randomly divided into experimental and control groups (n=25). The jas seal V6 electric oral irrigator and orthodontic toothbrush were used during orthodontic treatment in the treatment group, and only orthodontic toothbrush was used in the control group. Clinical periodontal indices, including plaque index (PLI), gingival index (GI) and sulcus bleeding index (SBI) of Ramfjoid index teeth were examined before orthodontic treatment and three months after treatment. Results: The periodontal indices had no difference between experimental and control groups before treatment (P>0.05). The periodontal indices in experimental group were obviously lower than those of control group after 3 months (P<0.05). Conclusion: The oral irrigator can reduce the plaque, and it should be used as an auxiliary method to prevent and control periodontitis in adult orthodontic treatment with fixed appliance.