With the development of the semiconductor, new energy engineer fields, the detection of hydrogen sulfide (H₂S) with extremely low concentration has received increasing attention. To solve the difficulties in the trace H₂S detection, this work combined the preconcentration technology with the cavity ring-down spectroscopy (CRDS), and established the preconcentration-CRDS system to detect the trace H₂S impurities. This paper systematically introduced the selection of solid adsorbents, system structure design and experimental schemes. Based on the detectable concentration of CRDS (0.5 µmol/mol H₂S), the H₂S concentration in the preconcentration experiment was demonstrated, and the quantitative relationship between the concentration maximum in desorption stage and the initial concentration of H₂S was established. The system performance, including reproducibility and the detection limitation, was analyzed in detail. Finally, the H₂S concentration in six fuel gases (CH₄，C₂H₆，C₂H₄，C₃H₈，C₄H₁₀ and CO) was determined quantitatively based on the established system. Based on the production processes and the experimental results, the possible sources of H₂S in different fuel were analyzed. The preconcentration - CRDS system in this study shown an excellent performance in trace H₂S detection, which offered an innovative approach to monitor the H₂S with the extremely low concentration.