A method was developed for the determination of butene-fipronil residue in dry samples by multiple adsorption synchronous purification (MASP) -gas chromatography (GC) -mass spectrometry (MS). After extracted with 1% acetic acid-acetonitrile, the samples were pretreated with MASP method including extraction, salting-out and purification procedures, and analyzed with GC-MS under the selected ion monitoring (SIM) mode, and then quantified by matrix-match standard solution with external standard method. The results showed good linearity in the range of 2 - 100 microg/L with the correlation coefficients (r(2)) not less than 0.999. The average fortified recovery of butene-fipronil in samples was found in the range of 92.2% - 97.5% at three fortified levels from 2 to 10 microg/kg, with the relative standard deviations of 2.69% - 5.21% (n = 6). The limit of detection (S/N = 3) for butane-fipronil was 2 microg/kg and the limit of quantification (S/N = 10) was 6 microg/kg. The method is simple, rapid and accurate, and could be used for the routine analysis of butane-fipronil in dry samples. Meanwhile, the pyrolysis mechanism of butane-fipronil, as a new substance, is discussed.