A method was developed and applied to determine the residual dicofol in eel by gas chromatography-mass spectrometry (GC-MS). The residue was extracted from homogenized tissue with acetonitrile-water assisted by n-hexane, separated with liquid-liquid partition. A part of the supernatant was purified using solid phase extraction (Florisil column) prior to the GC-MS analysis. The determination was performed in selected ion monitoring (SIM) mode with the external calibration for quantitative analysis. Under the optimized conditions, the quantification limit of the method (S/N = 10) was lower than 0.01 mg/kg. The recovery of the method for the spiked standard at the concentration of 0.01-0.1 mg/kg was 91%-105% with the relative standard deviation (RSD) of 4.3%-6.1%. The method is easy, fast, and more sensitive. The method can meet the requirement of the determination of dicofol in eel.