As a crucial strategy for the sustainable exploitation of potassium resources in salt lakes, water-replenishment-induced mineral dissolution plays a vital role in safeguarding national strategic interests. This study conducted a combined investigation of the mineral composition of brine-storing layers and the spatiotemporal distribution of brine hydrochemistry in the Dabuxun segment of Qarhan Salt Lake. The results indicate that the brine-storing layers exhibit distinct vertical mineral zonation: the shallow zone (0 – 4 m) is dominated by halite, with a maximum content of 95%; the middle zone (4 – 9 m) is enriched in carnallite (10% – 31% content), accompanied by bischofite; and the deep zone (>8 m) shows an increase in detrital minerals. Brine differentiation is controlled by Na?, Mg2?, and K?. The horizontal high-value belt of K? between the water-replenishment channel and the brine-extraction channel, as well as the vertical “chemical inflection point” where Mg2?, Cl?, and K? increase synchronously, reveal that water level dynamics are the key factors regulating the vertical migration and enrichment of potassium. Two brine replenishment methods exist in the study area: natural lake water recharge and artificial channel replenishment. The former has a broad influence range and long duration, with a significant dissolution effect on solid potassium salts in the shallow and middle layers. The latter extends the replenishment coverage, characterized by strong directionality but limited spatial scope. Overall, the study demonstrates that mineral dissolution induced by current artificial water replenishment still holds great potential in the shallow and middle layers. Therefore, it is necessary to optimize the replenishment layout and enhance the penetration capacity of low-mineralization water into target layers to improve the dissolution and extraction efficiency of potassium salt resources. This research elucidates the coupling mechanism among mineralogy, hydrochemistry, and hydrodynamics, providing a fundamental scientific basis for water-replenishment-induced mineral dissolution in Qarhan Salt Lake.