Hydrogels are more and more attractive in biomedical fields, since they can be used as injectable scaffolds, drugs and gene carriers and smart sensors. The highly hydrated hydrogels, however, generally have low mechanical strength. In this work, a composite chitosan hydrogel was prepared by blending water soluble and crosslinkable chitosan derivative (CML) with poly(lactic-co-glycolic acid) (PLGA) particles whose surfaces were grafted with double carbon bonds containing gelatin (GM), following gelation under UV irradiation. The as-prepared composite hydrogel showed lower swelling ratio than that of the CML hydrogel, and higher elastic stiffness (i.e. storage modulus) than that of the CML hydrogel and the hydrogel filled with the same amount of PLGA particles or gelatin modified PLGA particles. Moreover, the storage modulus of the composite hydrogel was increased with the amount of GM modified PLGA particles. In vitro chondrocyte culture revealed that viability of the cells co-cultured with the GM modified PLGA particles was higher than that of the cells co-cultured with the unmodified PLGA particles. The composite hydrogel blended with the GM modified PLGA particles also showed higher cytoviability than that of the original CML hydrogel after 9d culture.