Abstract: Potassium-magnesium sulfate fertilizer without pharmaceutical pollution was prepared by thermally dissolved cold crystallization technology with potassium-sulfate mixed salt mine from solar evaporation of sulfate-type West Taijinar salt lake brine as raw material. Results showed that the preparation technology of potassium-magnesium sulfate fertilizer with thermally dissolved cold crystallization method was feasible.The mass ratio of potassium to sulfate and granularity of the mine，thermally dissolved temperature and time，and cooling temperature and time were the main conditions affecting potassium yield.Optimum technological conditions of the preparation of potassium-magnesium sulfate fertilizer were obtained by single-factor experiments，such as different granularities，different thermally dissolved solvents and mixture ratios，reaction liquid quantities， and thermally dissolved temperatures and times etc..

Key words: potassium-magnesium sulfate fertilizer, thermally dissolved cold crystallization, potassium-sulfate mixed salt mine