In view of the scaling anion CO32– concentration and enrichment in the co-production process of salt-nitrate, which leads to scaling problems in the evaporation system, the study used multi-stage hydrochloric acid to adjust the brine pH to convert CO32– to HCO3–, alleviating system scaling and extending the production cycle effectively. The results of thermodynamic calculation, XRD, SEM-EDS and other technologies show that the conversion behavior of CO32– and HCO3– during the acid addition process was explored, and the following conclusions were drawn. The scale of the salt and nitrate evaporation system is mainly composed of CaCO3 scale and Mg(OH)2 scale, thought the scaling mechanism is different. The cause of scaling in the salt system is that the gradually enriched Ca2 forms low-solubility CaCO3 as the temperature rises, and the supersaturated state deposits and precipitates to form a scale layer. The theoretical calculation and experimental results indicate that adjusting the pH of the mother liquor of the nitrate system to 9.0 ~ 9.5 can convert local CO32– to HCO3–. The leaching experiment of scale layer shows that adjusting the pH of brine to 9.08, the Mg2 can be dissolved and leached effectively, but only a small part of Ca2 were dissolved and leached. The SEM-EDS results show that the dense scale layer formed by the un-leached calcium can inhibit scale formation on the surface of the heat exchanger, realizing the conversion of CO32– to HCO3– while preventing system corrosion, and alleviate system scale inhibition and prevention effectively.