Abstract: Using hydride generation to determine selenium in geological samples, the sample dissolution, selenium pre-reduction and the suppression of coexisting ion interference should be considered. In this study, concentrated hydrochloric acid was added to reduce Se(Ⅵ) to Se(Ⅳ) after the sample was dissolved by nitric acid, hydrochloric acid, hydrofluoric acid and perchloric acid. The trace selenium in the sample was determined by hydride generator coupled with Inductively Coupled Plasma-Optimal Emission Spectrometry (ICP-OES). The ions in the sample had no interference on the determination of selenium except Cu²⁺. Adding ferric salt solution to the sample solution or adding potassium ferricyanide to the reductant are beneficial to suppress the interference of Cu²⁺. The detection limit of this method was 0.12 μg/L, which is lower than that of a previous study, and RSD was less than 5%. The method was rapid and needed 30 seconds rinsing to eliminate the memory effect, which makes it suitable for the determination of trace selenium in uranium-bearing geological samples.