Abstract: Geosmin ( GSM) , produced by microorganism in Daqu, is the important cause of earthy- mouldy off-flavor in Chinese liquor.A simple and fast method based on headspace solid- phase microextraction ( HS- SPME) coupled with gas chromatography- mass spectrometry ( GC- MS) was established for the determination of GSM in Daqu. The analytes were extracted by atmospheric distillation with ethanol solution, and then extracted by HS- SPME using 75μm CAR / PDMS fiber.After concentrating, the sample was analyzed by GC- MS and quantified by the external standard method. The linear ranges were from 100 ng / kg to 8000 ng / kg for GSM, the correlation coefficient ( r) of the calibration curves was 0.999. The recoveries and the relative standard deviations ( RSDs) of GSM in Daqu were investigated.The recoveries ranged from 89.19% to 98.49% with the RSDs between 2.15% and3.06% ( n = 5) .The limit of detection ( LOD) was 42.6ng / kg, and the limit of quantification ( LOQ) was 140.6ng / kg.The method is suitable to the determination of GSM in Daqu.