Abstract: Hydride Generation (HG) combined with Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES) has excellent analytical sensitivity. However, the instable chemical reactions of HG may cause unsatisfactory analytical precision. In this study, a novel and self-made HG system coupled with ICP-OES was developed for measurement of As, Sb and Bi in geological samples. Inner diameter (i.d.) of introduction tubing changed from 0.32 mm to 0.76 mm. Reaction tubing i.d. changed from 0.76 mm to 1.14 mm and length increased from 30 cm to 50 cm. These changes significantly improve the stability of HG reaction by increasing space and time of chemical reactions to reach reaction equilibrium. Arsenic, Sb and Bi were firstly leached from soil and stream sediment using HCl-HNO₃ water bath, pre-reduced by thiocarbamide-ascorbic acid mixture, and were finally determined by the modified HG-ICP-OES. The detection limits of this method are 0.35 μg/g, 0.33 μg/g and 0.25 μg/g for As, Sb and Bi, respectively. The linear ranges are 1.1-300 μg/g for As, 1.0-100 μg/g for Sb and 0.75-100 μg/g for Bi, which is sufficient for the measurement of As, Sb and Bi in geological samples.