Abstract: Objective To analyse the clinical efficacy of treating periodontal- endodontic combined lesions in 140 cases. Methods 160 teeth with periodontal-endodontic combined lesions in 140 patients were selected and divided into three groups randomly. Group A was treated with combined method of root canal therapy and periodontal therapy at the same time. Group B was treated with periodontal therapy 2～3 months after the root canal therapy. Group C was treated with root canal therapy. Results After one year, the clinical treatment effects of Group A were superior to those of Group B, but there was no statistical significance(P>0.05). The clinical treatment effects of Group A and Group B were superior to those of Group C obviously, and there was statistical significance(P<0.05).Conclusion Combined method of thorough root canal therapy and seasonable periodontal therapy is effective to treat periodontal pulp combined lesions, which can increase teeth' survival rate.