Objective To investigate the effect of Erbium laser in the treatment of moderate to severe periodontitis and its influence on the level of osteocalcin.Methods A total of 112 patients with moderate to severe periodontitis admitted to the Department of Stomatology,Dalian Friendship Hospital from January 2017 to December 2020 were selected as the research subjects,and they were divided into control group (56 cases)and experimental group (56 cases) according to the random number table method.The control group was treated with conventional treatment methods,while the experimental group was treated with Erbium laser.The clinical outcomes,osteocalcin levels in the gingival sulcus fluid at 1,3,and 6 months after treatment,and serum indexes (tumor necrosis factor-α [TNF-α],serum interleukin-1β [IL-1β],interleukin-6 [IL-6]and C-reactive protein [CRP]) level before and after treatment were compared between the two groups.Results The total effective rate of treatment in the experimental group was higher than that in the control group,with statistically significant difference(P＜0.05).At 1,3,and 6 months after treatment,the levels of osteocalcin in the gingival sulcus fluid of the patients in the experimental group were lower than those in the control group,with statistically significant differences(P＜0.05).The levels of TNF-α,IL-1β,IL-6,CRP after treatment in two groups were lower than those before treatment,with statistically significant differences(P＜0.05).After treatment,the levels of TNF-α,IL-1β,IL-6,CRP in experimental group were lower than those in the control group,with statistically significant differences (P＜0.05).Conclusion The Erbium laser treatment of patients with moderate to severe periodontitis can not only achieve good clinical treatment effects,but also improve the level of osteocalcin at each point in time can improve the serum index level after treatment,which has promotion value.