The utility model provides a chloride ion detection device based on spectral analysis. A chlorine ion detection device relates to the field of chlorine ion detection, and comprises a light source, a flow cell, a spectrograph, a controller, a display, a water sample bottle, a reagent bottle and a reaction chamber for mixing a water sample and a reagent, the water sample bottle and the reagent bottle are respectively connected with the reaction chamber through a peristaltic pump, and the reaction chamber is connected with the flow cell through the peristaltic pump. According to the chloride ion detection device based on spectral analysis, the content of chloride ions in a solution is predicted by analyzing spectral information, so that the purpose of detecting the concentration of chloride ions in the solution is achieved, the problems of complex operation, long detection time and the like of rapid detection of chloride ions in an oil refinery are solved, and the device has the advantages of simple operation, high detection efficiency and the like.