The invention relates to the field of high-value products recovered from industrial waste, in particular to a method for preparing cesium sulfate in saline waste water. First, an extractant is prepared, and t-BAMBP, P 204 and kerosene, the t‑BAMBP, P 204 Mix it with kerosene to prepare the extractant, then detect the ion concentration of the feed liquid, and then take the saline wastewater to adjust the pH, and then perform multi-stage countercurrent extraction on the feed liquid with the post-extractant to obtain a loaded organic phase, and then use the washing liquid to The organic phase is loaded for circulation countercurrent washing, then the stripping agent is made, stripping is carried out, and finally cesium sulfate is obtained by evaporation. Realize the separation and extraction of cesium in saline wastewater, and use the weak alkalinity of saline wastewater to provide a method based on t-BAMBP and P under alkaline conditions. 204 Cooperative extraction of cesium in saline wastewater.