An extraction method for the determination of methyl-tert-butyl ether(MTBE) in the water, based on the pretreatment methods of solid-phase microextraction(SPME), coupled with GC-mass spectrometry, was developed and tested. The methyl-tert-butyl ether in aqueous solution was extracted by using SPME fiber coated with adsorbent, then analysed with GC-MSD with capillary column. The effects of the Extraction parameters(pH, extraction times and salt saturation)on the extraction efficiency were studied and the method was then applied to determine MTBE in the water. The obtained results showed good analytical performance in terms of precision (3-8%, RSD) and accuracy(93-102%, mean recovery) with a method detection limit of 0.03 ppb.