A n-octadecyl（C18）solid-microextraction fiber was prepared by sol-gel technology,and used in the extraction of organochlorine pesticides in water samples.The sol-gel solution was prepared by mixing appropriate amount of n-octadecyltriethoxysilan（C18-TEOS）,tetraethoxysilane（TEOS）,ethanol,hydrochloric acid and water.Then the n-octadecyl solid phase microextraction fiber was obtained from the polymerization of the sol-gel solution on the surface of the treated fused-silica fiber.Under the optimum conditions,the detection limits of organochlorine pesticides（OCPs）by gas chromatography with electron capture detector（GC/ECD） after extraction with the new C18 fiber were in the range of 0.01-0.24 μg/L,and the relative standard deviations（RSDs） varied from 3.0% to 13.3%.The method was applied in the detection of organochlorine pesticides in fishpond water,lake water and drinking water with satisfactory results.The extraction ability of the new fiber for OCPs was not changed significantly after it was dipped into four kinds of solutions（e.g.n-hexane,methanol,pH 2.0 and 9.0 water solutions） and repeatedly used for 50 times.The obtained fiber showed several advantages including porous structure,high stability and uniformly coating,and could be used as an alternative to the existing fibers for the extraction of OCPs.