The invention relates to a novel solid phase micro-extraction stainless steel fiber and a preparation method thereof, which provides a method for easily and rapidly preparing the solid phase micro-extraction stainless steel fiber with high stability and high reproducibility. The preparation method is as follows: soaking the part of cleaned stainless steel wire into acid for treatment; washing by water; ageing under the protection of nitrogen, obtaining the solid phase micro-extraction stainless steel fiber; mounting the prepared solid phase micro-extraction stainless steel fiber in a microliter syringe, obtaining a simple solid phase micro-extraction device. The method is simple in operation and low in cost. The prepared solid phase micro-extraction stainless steel fiber has excellent extraction performance on all trace amount organic pollutants. Compared with commercial solid phase micro-extraction device, the solid phase micro-extraction device has better mechanical strength and thermal stability, and has low cost and long service life. The extraction fiber has excellent application potential in fields of environmental monitoring, food hygiene and the like.