disclosed is a method for preparing a magnetic microsphere for the separation of biological proteins . a magnetic microsphere matrix is treated by formulating and using an appropriate emulsified liquid , and modification of the surface of the magnetic microsphere matrix is realized by emulsion polymerization , thereby obtaining a magnetic microsphere coated with a polyacrylate polymer layer . said emulsified liquid comprises the following components therein : acyclic acid monoester compounds , acyclic acid glycol compounds , initiators and optionally anionic surface active agents and water . the magnetic microsphere significantly reduces the non - specific adsorption of other proteins , without affecting the joining ability for a specific protein , when used in the separation of biological proteins . a new selection is provided to realize the separation engineering of high protein specificity adsorption .