The invention discloses a preparation method of an SPME (solid-phase microextraction) head with a porous activated carbon membrane coating. Modified stainless steel wires are selected as a carrier, polyacrylonitrile is dissolved in a ternary mixed solvent, and the surfaces of the stainless steel wires are coated with polyacrylonitrile porous membranes with a steam assistance method; the stainlesssteel wires with the polyacrylonitrile coating membranes are soaked in an acetic acid solution and a potassium permanganate solution respectively; finally, the stainless steel wires with the polyacrylonitrile coating membranes are preoxidized and carbonized, so that the polyacrylonitrile porous membranes are converted into porous activated carbon membranes, that is, the surfaces of the stainless steel wires are coated with the porous activated carbon membranes in situ, and the SPME heat with the porous activated carbon membrane coating is obtained. The SPME head has the characteristics of highmechanical strength, excellent adsorption performance, good reproducibility, long service life and the like and can be used for trace component enrichment analysis of actual samples of food, environment, medicines, biochemical products and the like.