Polysaccharide-based thermosensitive injectable hydrogels, as a class of smart soft-matter materials, are capable of realizing reversible liquid-solid transition under different temperature stimuli, and have the advantages of high biocompatibility, biodegradability, and tunable physical and chemical properties, which have attracted wide attention in the biomedical field. In this review, the sol-gel phase transition mechanism of thermosensitive injectable hydrogels is summarized; The strategies of designing and synthesizing polysaccharide based thermosensitive injectable hydrogels were described, including small molecule group modified polysaccharide, synthetic thermosensitive polymer grafted polysaccharide, additive modified polysaccharide, etc.; The applications of polysaccharide based thermosensitive injectable hydrogels in biomedical fields such as wound healing, drug delivery and cartilage repair were reviewed, The challenges of optimizing raw material composition and design strategy, developing diversified environmental stimulus responses, and enhancing mechanical strength and stability are also suggested. Finally, the prospect of expanding the application scope of polysaccharide-based hydrogel and accelerating their wide-scale clinical application is prospected.