Abstract: A new kind of composite hydrogel based on Sodium Alginate (SA) and poly (N-isopropylacrylamide) (PNIPA) cross-linked by inorganic clay (Laponite XLG) was synthesized. The structure and morphology were characterized by means of FT-IR，XRD and SEM. Swelling behavior and mechanical properties of these novel hydrogels were also studied. The results showed that the regular crystal structures of clay were destroyed and the clay platelets were exfoliated and dispersed randomly in the hydrogels，which acted as a multifunctional crosslinker in the hydrogels. As the clay contents increased，the crosslinking density of hydrogel increased and the pore size decreased，which led to the decrease of the swelling rates of the hydrogels. Moreover，the PINPA/SA/clay hydrogels exhibited good mechanical properties with the elongation at break more than 1000%.