Provided are a polymer having ultraviolet absorption functionality and preparation method thereof; specifically, three monomers having different ultraviolet absorption bands are used for copolymerization, achieving a significant expansion of the ultraviolet absorption range and achieving the effect of full-band ultraviolet shielding. The obtained polymer film has strong visible light transmittance, fluorescence, easy processing, excellent stability, and remarkable ultraviolet shielding performance, and can be broadly applied in such areas as aviation, construction, agriculture, and optical devices.