Objective:To observe the effects of Er ∶YAG(erbium:yttrium-aluminum-garnet) laser combined with diode laser in the treatment of chronic periodontitis.Methods:30 patients with chronic periodontitis patients were treated by mechanical scaling and root planning(SRP),pure Er ∶ YAG laser(ERT),diode + Er ∶ YAG + diode laser therapy(TPT) respectively.In the treatment VAS pain score was recorded.Probing deepth (PD),clinical attachment level (CAL) and bleeding on probing (BOP) were examined,IL-1 β,TNF-α and b-FGF in GCF,Porphyromonas gingivalis(Pg) in subgingiva plaqure were measured before and after treatment.Data were analyzed by SPSS 21.0 software.Results:6 weeks,12 weeks after treatment PD,BOP and CAL in TPT group were lower than those in ERT and SRP groups(P ＜0.05),TGF-β and b-FGF in TPT group were higher,IL-1β and TNF-α were lower than those in ERT and SRP groups (P ＜ 0.05).The content of Pg relative to total bacteria in TPT group were lower than that in ERT and SRP groups (P ＜ 0.05),VAS value in twinlight laser group was significantly lower than hand instruments group(P ＜ 0.05).Conclusion:The twinlight laser is effective in the treatment of periodontitis.