Abstract: A home-made open-loop stripping analysis (OLSA) system was developed for determining five earthy-musty compounds in water by gas chromatography. The purified air was used as stripping gas, and the glass tube as heating line, which reduce greatly the background level and adsorption during the analysis. In addition, activated carbon filter, extraction mode and inorganic ionconc entration in water were compared and optimized. The results showed that the detection limits for these five odorants were low to 1.5ng/L, the mean recoveries and the precision ranged from 99.8%～115% and 4.8%～11.6% (±S.D.%) respectively.