The invention discloses a preparation method for maleoyl chitosan polymer microspheres. The preparation method comprises the following steps of: adding an oil phase solvent, a small amount of emulsifier and monomer into a flask; adjusting rotation speed; heating to 65 DEG C; adding maleoyl chitosan aqueous solution and ammonium persulfate initiator after 0.5 hour; heating to 75 DEG C and uniformly stirring; then adding aqueous crosslinking agent N,N-methylene-bisacrylamide and reacting for 1-6 hours; cooling a product to room temperature; washing for 3 times by using the oil phase solvent; removing unreacted reactant and byproduct; AND washing for 3 times with absolute ethyl alcohol or acetone by using a gradient elution method to obtain the AMCS (Magnetic Activated Cell Sorting) microspheres. The microspheres are high molecular microspheres with smooth outer surfaces and internal honeycomb structures; a template is not required to be removed; the method is easy and convenient to operate; and the activity of an embedding substance can be maintained to the greatest extent. The microspheres can be used as a medicament control and release catalyst carrier, and have broad application prospect and practical value.