Thereare 296 million tons of low- grade solid potash minerals in the Qarhan salt lake, which have potential utilization value.These low- grade solid potash minerals are equivalent to a super large potash deposit. The low- grade solid potash minerals can be transformed into brine with the same properties as the intercrystalline brine existing in the salt layers through the dissolution transformation technology. In this paper, the dissolution and transformation process of low- grade solid potash ore in the Qarhan salt lake was simulated by PHREEQC software in order to quantify the process. The transfer amount of the main minerals in the process of potash ore dissolution was calculated by simulation. The results show that in the process of potash minerals dissolving in per 1L solution, the amount of gypsum precipitation is between 10.85 and 12.97 mmol, the amount of halite dissolved is between 494.2 and 1616 mmol, the amount of polyhalite dissolved is between 0.63 and 3.119 mmol, the amount of carnallite dissolved is between 4.732 and 380.2 mmol, the amount of sylvite dissolved is between 63.64 and 387.6 mmol, the amount of calcite dissolved is between 0.141 and 0.381 mmol, and ion exchange capacity between NaX and MgX 2 is 101.1 to 918 mmol. The study indicates that the main potash minerals in Qarhan salt lake are polyhalite, carnallite and sylvite. The dissolution of these potash minerals causes the content of K+ in the solution to continuously increase. However, the increase in K+ concentration in liquid phase is different in different areas, which is caused by the differences in the geological structure of salt bed and the uneven distribution of potash minerals. It is proposed that the dissolution of polyhalite is the main reason for the precipitation of trace gypsum. Due to the high concentration of MgCl 2 in the solvent, the same- ion effect and cation exchange between NaCl and MgCl 2 jointly controls the solubility of halite in liquid phase.