The work aims to prepare a spongy film with agar and chitosan-oxidized microcrystalline cellulose graft (CS-g-MCC(O)) as raw materials, and study the application of film in surgical dressing. The agar and chitosan-oxidized microcrystalline cellulose grafts were mixed in different proportions by blending method, and then the film was obtained by freeze-drying method, and the porous structure was characterized by scanning electron microscope; the swelling ratio, dissolution rate, water vapor transmission rate and mechanical properties of the film were tested. The prepared sponge dressing had regular morphological structure and obvious pores, which were helpful for the discharge of metabolites in the wound; with the increase of the agar content, the dissolution rate of the sponge dressing decreased first and then increased. The swelling ratio, porosity, moisture permeability, tensile strength and elongation at break increased first and then decreased. Sponge dressing is relatively excellent in all properties. These excellent properties are beneficial to the absorption of wound exudate and the growth of cells, which plays an important role in wound healing and promote its application in medical dressing.