Abstract: Objective: To compare the periodontal health between orthodontic patients with fixed orthodontic appliance and invisible aligner. Methods: A total of 30 patients were randomly divided into two groups. Invisible aligners were used in the experimental group, while fixed orthodontic appliances were used in the control group. Gingival crevicular fluid volume (GCF), AST and ALP in GCF were measured before treatment and 6 months after treatment respectively. Results: Six months after treatment, GCF, AST and ALP in the experimental group were lower than those in the control group (P<0.05). Conclusion: During the observation period, invisible aligner is more propitious to periodontal health than fixed orthodontic appliance.