A method was developed for the determination of cyanogen and hydrogen cyanide residues of fumigant in soil using gas chromatography with purge and trap.The working parameters were optimized using spiked lab blank samples．The results showed that the optimum conditions were found to be as follows:purge time:60 min，purge temperature:80 ℃,purge velocity of carrier gas(N2):40 mL?min-1and 10% sulfuric acid as acidifying reagent.The calibration curves were linear over 0.2-10 mg?L-1 of cyanogen and hydrogen cyanide with correlation coefficients of 0.999 1 and 0.998 3，respectively.Under the optimal conditions，the average recoveries of spiked cyanogen and hydrogen cyanide were 95% and 96%，respectively，with RSDs (n=6) of 3.6% and 5.2%，respectively．The limits of detection(LOD，S/N=3) of cyanogen and hydrogen cyanide were 0.012 and 0. 021 mg?kg-1，respectively，and their limits of quantitation(LOQ，S/N=10) were 0.040 mg?kg-1 and 0.070 mg?kg-1，respectively．After 48 hours of fumigation with cyanogen at 100 mg?kg-1，the residues of cyanogen and its degradation product——hydrogen cyanide in aged soil were 0.32 mg?kg-1 and 5.68 mg?kg-1，respectively．This method was also proved to be convenient in operation with high precision and accuracy，and could be applicable in the determination of cyanogen and hydrogen cyanide residues in aged soil.