Taking advantage of the feature that dialdehyde xylan (DAX) can react with carboxymethyl chitosan (CMCS) and silver ammonia solution at the same time, that is, the aldehyde group of DAX reacts with the amino group of CMCS to form an imine bond, and at the same time, A large number of aldehyde groups contained in DAX undergo a silver mirror reaction with silver ammonia solution, and silver nanoparticles (SNPs) are quickly reduced at room temperature. Carboxymethyl chitosan-nanoparticles with excellent antibacterial properties were prepared by one-pot method. Silver antibacterial hydrogel. Polyvinyl alcohol (PVA) with good biocompatibility was added and a double network structure interpenetrating with CMCS was formed by freeze-thaw method, which further improved the structural stability of the hydrogel. The morphology and structure of DAX, SNPs and hydrogels were characterized by FTIR, thermogravimetric, TEM, XRD and SEM. The results showed that DAX played a very effective bifunctional role in the whole reaction, and successfully reacted with CMCS and PVA to form a hydrogel with a double network structure, thereby improving the mechanical properties of the hydrogel. At the same time, DAX reduces the SNPs in the silver ammonia solution, and the particle size is between 20-80 nm, which has good dispersibility, thereby significantly improving the antibacterial properties of the hydrogel. The hydrogels prepared herein have potential applications in wound dressings.