A series of polylactic acid-polyethylene glycol-polylactic acid diacrylate macromers (PEGLM) were synthesized, and a novel chitosan-PEGLM double network (DN) hydrogel was further successfully fabricated by the sequential interpenetrating technology with highly cross-linked chitosan as the rigid component and PEGLM as the flexible component. Their structures and components were characterized by 1H NMR, FTIR, and XRD. Their fracture morphology was investigated by SEM. It was interesting to found that the compressive strength of hydrogel wound reach its maximum value when the chitosan content was 10%, no matter what the molecular weight of PEGLM component was. What’s more, we found that the compressive strength of 6KL7 could reach 1.07 MPa at gel state, whose PEG segment molecular weight was 6,000, and polymerization degree of PLA was 7. The effects of glutaraldehyde ratio, polymerization degree of PLA, and molecular weight of PEG segment on the mechanical strength of DN hydrogels were also discussed in this article. To further strengthen DN hydrogels, the double network-linear (DNL) hydrogels were fabricated by introducing linear poly(vinyl alcohol) (PVA) into the DN hydrogels. The DN-L hydrogels exhibited better mechanical properties, with the compressive strength up to 1.45 MPa. These hydrogels may have prospective applications in the fields of wound dressing, artificial cartilage and tissue engineering scaffold materials which require high mechanical properties.