Abstract: For effective detecting of 2, 4-Dichlorophenoxyacetic Acid (2, 4-D) residue in orange fruit, a quick analytical method was developed. After extracted by acidic acetonitrile, the filtrate was purified by acid diatomite. The target compound in sample was derivatised by Trimethylsulfonium Hydroxide (TMSH), and then determined by GC-ECD. The results suggested that the lowest detection limit for 2,4-D was 5×10-13g, and the limit of quantification was 4×10-4mg/kg. The recoveries of 2,4-D from orange spiked with 0.001, 0.01, 0.1mg/kg ranged from 77.16 to 92.72%，with the coefficient of variation of 3.30 to 8.65%. This method is rapid, accurate, sensitive, and of good reproducibility．It can be used to determinate 2, 4-D in orange fruit.