A method of preparing large-size high-porosity Fe-doped photocatalytic porous magnetic microspheres, including: dissolving a soluble macromolecule in a distilled water to obtain a solution A having a concentration of 0.5-1.5 wt %; adding a photocatalyst to the solution A, and uniformly stirring the solution A to obtain a suspension B; mixing a saturated soluble ferric salt solution with the suspension B, and uniformly stirring the mixture to obtain a suspension C; dropwise adding the suspension C to a high-concentration alkali solution by a syringe equipped with a suitable needle size to form microspheres; ageing the reaction system and drying the formed microspheres after adding; calcining the dried microspheres at 600-1100° C.; cooling the calcined microspheres to obtain the large-size high-porosity Fe-doped photocatalytic porous magnetic microspheres.