The invention discloses a polymer microsphere and preparation thereof and application thereof in preparation of antibody purification filler. The polymer microsphere is prepared by the following steps of: taking polyvinyl alcohol and sodium alginate as raw materials, adding water to dissolve at 80-100 DEG C, cooling to 40 DEG C, and adding a recombinant escherichia coli solution containing ZZ fusion protein to prepare a water phase; and mixing liquid paraffin and a surfactant to form an oil phase, slowly dropwise adding the water phase into the oil phase, stirring at 30-70 DEG C to form emulsion, and adding a saturated boric acid calcium chloride aqueous solution to prepare the polymer microsphere, wherein the ZZ fusion protein is formed by fusing ZZ protein and ankyrin (LppOmpA) through a connecting peptide. The diameter of the polymer microsphere prepared by the method is 50-250nm, the ultra-large pore diameter is 1-2 microns, the raw materials are cheap, the cost is low, the operation is simple, the preparation processes of expression, purification, grafting and the like of conventional ligands are omitted, and the problems of expensive ligands and the like are solved.