Phosethy-Al residues in tobacco leaves and soils were analyzed by Gas Chromatography (FID). In this method residues of phosethy-Al transformed into ethanol gas in alkali liquid, the content of ethanol in FID was determined with tert-butyl alcohol as inner demarcate, then the content of phosethy-Al was calculated according to the content of ethanol. Results showed that the fortified recovery in leaves and soils was above 84.0% and relative standard deviation was under 8.50%. The minimum residue in fresh leaves, soils and dry leaves were 0.01, 0.01 and 0.05 mg/kg, respectively. The half life in leaves and soils ranged in 2.44-3.14 days and 6.20-8.98 days, respectively. The ultimate residue in leaves was lower than 0.68 mg/kg, and in soils was lower than 0.31 mg/kg, which could fulfill the residue analysis requirement.