Redox-responsive ferrocene (Fc)-containing hydrogels have attracted increasing interest for their potential applications in materials science, biomedicine and catalysis. Herein, we report the synthesis of a novel poly-norbornene-based tetrablock terpolymer containing consecutively aldehyde, Fc, and dentritic triethylene glycol and aldehyde groups in the side chain by the ring-opening metathesis polymerization with the aid of the 3rd generation Grubbs catalyst. Owing to the presence of Fc and triazole groups, this copolymer could be used as both reducing and stabilizing agents for the formation of silver nanoparticles (AgNPs). Also, this copolymer could be used as a crosslinking agent to fabricate gelatin hydrogels based on the Schiff's base reaction between the aldehyde groups and the side-chain amino groups of gelatin. Based on the above properties, the AgNPs composites of gelatin hydrogels were further successfully fabricated by blending this copolymer, gelatin and AgNO3 together or soaking this Fc-containing gelatin hydrogels into the AgNO3 solution, in which the Ag-I was in situ reduced into Ag-0 by the Fc groups. Results of inhibition zone experiments confirmed the antibacterial activities of the obtained composites against both Escherichia coli and Staphylococcal aureus.