To clarify the spatial distribution characteristics of major potash minerals in low-grade solid potash ores and their implications for water-solution mining performance in the Bieletan mining area of the Qarhan Salt Lake, this study used drill core samples obtained from the 2022 reserve verification project. X-ray diffraction analysis was conducted, and chemical analysis data from both the general survey stage (1967 data) and the reserve verification stage were integrated to investigate the distribution patterns of major potash minerals, such as carnallite and polyhalite, as well as the variation characteristics of KCl content in the ore beds. The results show that halite is the overwhelmingly dominant mineral in the study area, while carnallite and polyhalite are the main potassium-bearing minerals, with the average content of polyhalite being higher than that of carnallite. Significant differences occur in the distribution of potash minerals between the upper and lower ore beds. Carnallite is mainly enriched in the northwestern part of the study area, whereas polyhalite is generally closely associated with carnallite and, in the southeastern part of the upper ore bed, shows spatial correlation with gypsum and clay minerals. Comparison between the general survey and reserve verification data indicates that, after large-scale solid-liquid conversion mining, the distribution of high-grade solid potash ores in the study area has become more dispersed. In the upper ore bed, the average KCl content has decreased and spatial dispersion has increased, whereas in the lower ore bed, KCl content has increased locally and its spatial distribution has become relatively smoother. Comprehensive analysis suggests that carnallite is the principal mineral preferentially dissolved during the solid-liquid conversion process, while the formation of polyhalite may be related to the mixing of K⁺- and Mg²⁺-rich brines released by dissolution with Ca²⁺- and SO^2-₄-rich brines or solvents. The results provide a geological basis for the efficient development, dynamic monitoring, and optimization of solution-mining engineering of low-grade solid potash ores in the Bieletan mining area.