The double network hydrogel with superior mechanical properties was prepared by rigid calcium alginate network and flexible polyacrylamide networkDuring the formation of rigid calcium alginate (ALG Ca) network，Ca2+ released from the EDTA Ca and then complexed with guluronic acid (G Unit) in the alginate forming ionically crosslinked and uniform alginate gelThe flexible polyacrylamide network (PAM) was formed by covalent crosslinking with the small amount of chemical cross linking agentThe effects of relative content of the two networks and the degree of crosslinking on the mechanical properties of the hydrogel were investigatedThe results showed that in a manner of releasing calcium ions from the EDTA Ca，optimum mechanical properties of the gel are obtained when the ALG/AM mass ratio is 02，BIS / AM mass ratio is 0002 and Ca2 + / COO- molar ratio is 06.
