The utility model relates to a stainless steel chlorine ion corrosion immunising self-warning device which is arranged on a return pipe of dyeing and printing equipment and belongs to a corrosion preventing device. The utility model is mainly composed of an alarm device, a sensor and a casing, and the alarm device tightly matched with a sensor device is arranged on the casing which is composed of an outer shell, a stator, corrosion preventing material, a flange connection pipe, and a flange. The utility model has the advantages of simple structure and strong corrosion resistance, enables the austenitic stainless dyeing and printing equipment to generate the immunization to the corrosion of the chlorine ion and meanwhile controls the corrosion of the equipment which generates the corrosion of the chlorine ion; after the corrosion preventing material is used up, the utility model automatically alarms, and the immune device can be changed at any time to prolong the service life of the equipment.