Objective To prepare a kind of core-shell functional microsphere. Methods Microspheres were synthesized by soap-free emulsion polymerization method with styrene ( St) , methyl methacrylate ( MMA) and acrylic acid ( AA) using APS as initiator. The structure of the microsphere was characterized by FT-IR, the morphology and particle size of the microspheres were evaluated by SEM and laser particle analyser. The water contact angel was measured by OCA. Factors influencing the morphology and particle size of the microspheres were well studied. And the variation of hydrophilicity of the functional microsphere film was studied at different temperatures. Results The as-prepared microspheres with PSt as core and MMA-AA as shell showed uniform morphology and excellent monodispersity. Conclusions The microsphere coated film showed the highest superhydrophilicity with a water contact angle of 3毅 at 25 益 .