Abstract: In this study, a rapid method for the determination of sulfides in seawater was developed using enhanced circulating absorption method in the closed system. Compared with the traditional methylene blue spectrophotometric method, the new method uses the enhanced circulating absorption in the closed system with automatic quantitative acid adding technique and without nitrogen blow and heating. The sample treatment time is less than 5 min, which is convenient and efficient for batch treatment of seawater samples. The closed system avoids the leakage of H₂S, and ensures the recovery rate (more than 80%) and precision. The method detection limit is 0.16 μg/L. The new method is rapid, accurate and efficient for sulfide monitoring in seawater, and can completely meet the demand of the marine environmental monitoring.