A series of fluorescent dextran hydrogels with typical three-dimensional sponge-like structure were prepared by the oxidation of dextran with sodium periodate and followed cross-linking with cystamine dihydrochloride via the aldehyde-amine Schiff base reaction. The effects of crosslinking density (-CHO/-NH2 molar ratio), dextran molecular weight and polymer concentration on the crosslinking time, microstructure, swelling properties and rheological properties of the obtained hydrogels were investigated, the results indicated that dextran hydrogel prepared with dextran T40, an oxidized dextran concentration of 75 mg/mL, and a -CHO/-NH2 molar ratio of 1.49 had the better three-dimensional network structure, viscoelastic properties and swelling properties. Furthermore, due to the presence of acid-sensitive Schiff base bonds and reduction-sensitive disulfide cleavage bonds, the resulted hydrogel exhibits pH/reduction dual sensitive degradation behavior, making it suitable for the application as an environmentally sensitive platform for local drug delivery.