Abstract: OBJECTIVE To establish a head space gas chromatography method for determination of ethanol, acetone, chloroform, pyridine and toluene residual solvents in active pharmaceutical ingredients of p-chlorophenoxyisobutyric acid methoxyphenyl acrylate. METHODS The experiment was carried out by headspace gas chromatography with a detector for the hydrogen flame ionization detector (FID) and the column for the Agilent DB-624 capillary column(30 m×0.32 mm, 1.8 μm). The sample was dissolved in DMSO solvent. The temperature of inlet was 200℃ and the temperature of detector was 250℃. The split ratio was set to 10︰1. Program temperature was used in the whole process, and the N₂ was used as carrier gas, H₂ and air were used as burn gas. The headspace balance temperature was 85℃, and the balance time was 30 min. In such conditions, the sample was injected 1 μL each time. RESULTS Ethanol, acetone, chloroform, pyridine and toluene could be completely separated in the established method, R were all <1.5, N were all <10 000; the linear relationship was good in the investigated mass concentration degree(r was 0.999 8, 0.999 8, 0.999 7, 0.999 6, 0.999 4); the limit of quantification was 19.83, 4.50, 48.28, 10.44, 2.08 μg·mL^-1, respectively; limit of detection was 3.97, 0.90, 9.66, 3.07, 0.69 μg·mL^-1 respectively; RSD were all >2.5%; the average recoveries were within 102.40%-106.45%; the reference substance kept stable within 24 h. CONCLUSION The method is simple, sensitive, with accurate and reliable results, which can be applied on the organic solvent residue control of p-chlorophenoxyisobutyric acid methoxyphenyl acrylate.