Periodontal tissue and pulp tissue can communicate each other by some anatomical structures, like accessory canal, lateral canal, apical foramen and dentinal tubule. Once lesion appears, it is possible to influence by the above passage to the other side. The treatment of peri-endo combined lesion needs endodontic root canal treatment first, then comes periodontal treatment or not. This paper presents the overall treatment of a patient with chronic periodontitis, where 47 received root canal therapy first, then using guiding tissue regeneration with bone graft was used to treat furcation involvement and bony defects. Followed by clinical data and radiographic analysis of the treatment area to observe the long-term effect by guiding tissue regeneration.