The invention provides a solid-phase micro-extraction fiber with a polymer coating and a preparation method thereof, which relates to the field of trace analysis of organic matters in food, environment and biological samples. The extraction fiber is formed by a carrier and a coating on the surface of the carrier, wherein the carrier is a metal fiber of which the length is 10-40mm and the diameter is 0.1-0.5mm, the coating comprises a polymer layer, and the polymer comprises one or more kinds of styrene divinylbenzene copolymer, crosslinked polystyrene or crosslinked polydivinylbenzene. The method comprises the following steps: selecting and preprocessing the metal fiber; coating a layer of high-temperature resistant epoxy resin or organic silicon resin; bonding a layer of polymer at the outer layer; curing the coating; and removing impurities. The invention can be used for forming a coating material which has good heat stability and solvent washing resistance, thereby realizing the purpose of enriching trace organic matters.