Potassium resources are one of the seven major scarce mineral resources in China. For a long time, China depends on imports for potassium resources. It is not easy to find potassium deposits in China. After more than 50 years' exploration, it is difficult to get a new breakthrough for potassium in the saline lake. There are hundreds of millions of tons of low-grade potassium in Qarhan Salt Lake, Mahai, and Lop Nur, equivalent to a large potash deposit. The development and exploitation of low-grade potassium is an important and feasible direction to solve the shortage of potash in China. In this paper, the authors carried out field experiments on liquefaction and exploitation of low-grade solid potassium in Bieletan, Qinghai Province, mainly studying the hydrodynamic and hydrochemical change. In the process of converting low-grade solid potassium into liquid, there exists big difference of water level change in different units of the experimental area in different periods, showing that there are significant differences in geological structure, tectonics, and especially porosity in Bieletan. In the process, the content change of KCl in the brine is different. In the initial stage of the process, the change of KCl content of brine in the detective pit is opposite to that of water level, and where the water level rises obviously, the quality of the brine is poor. However, with the constant replenishing of the solvent and the increasing of reaction time between solid potassium and solvent, the KCl content of the brine in the experimental area tends to become average, but the overall content is low. After months of liquefaction of low-grade solid potassium, the KCl content of the brine is still low and doesn't rise obviously. These phenomena may be attributed to the fact that many years mining of low-grade potassium has led to the reduction of potassium minerals in this area.