In order to adsorb proteins in wastewater, starch–chitosan composite film material, which can be used to adsorb proteins in wastewater, was prepared with starch and chitosan through cross-linking reaction. The introduction of starch makes the chitosan membrane material become more stable. Under the action of glutaraldehyde, starch cross-links with chitosan, forming a large number of hydrogen bonds and Schiff base structure. And after, the composite membrane material was soaked in water for 48 h to still maintain a stable form. Through the analysis of adsorption kinetics, adsorption thermodynamics, and adsorption isotherm equation, it is found that the adsorption of bovine serum albumin is more in line with the quasi-quadratic kinetic model and the Langmuir isotherm model, and the composite film material bovine serum protein (BSA) is a spontaneous adsorption process. Overall, the prepared composite film has great potential as a protein-adsorbing material and also provides an efficient utilization route for high-protein wastewater treatment.