Abstract: Recently, in situ gel has been widely used as a local delivery system for periodontitis treatment because of its lesion injectability, local drug depot function, and drug sustained-release effect.Different therapeutic purposes can be achieved by loading different types of drugs such as antibiotics, bioactive factors, etc.In this review, different types of in situ gel with temperature-sensitive, ion-sensitive, pH-sensitive and solvent-exchanged characteristics were introduced for their applications and limitations in the delivery of drug for periodontitis;and the elimination of periodontal inflammation, periodontal tissue repair and the long-term role after loading microsphere achieved by the in situ gel system were also reviewed.