Polyhalite resources are rich in China, but they have not yet been exploited because the polyhalite ore is difficult to dissolve and deepburied. According to the geological conditions of polyhalite deposit formation, the deposit has good sealed wall rocks and basic geological conditions of leaching mining. The technological key to leaching mining of underground polyhalite is the extraction of effective constitutes from polyhalite. Theoretical and experimental studies show that inorganic solutions such as CaCl2 solution may improve the dissolubility of polyhalite. Leaching mining is probably an effective way for the exploitation of deeply buried polyhalite. The technological factors influencing the dissolution process of polyhalite such as the concentration of the leaching agent CaCl2 solution, grain size of ore, infiltration rate and infiltration path were studied through experiments. The kinetic study of the dissolution process shows that the process of leaching polyhalite with calcium chloride solution accords with the kinetic model of metal leaching model constructed by В. С. ГолубевГ. Н. Крuчев. That is C=CH〖JB(［〗1－e〖SX(〗－γ（χ－vBt)〖〗U－vB〖SX)〗〖JB)］〗. There is an exponential relationship between the concentration of K+ in the leaching solution and the ratio of the infiltration rate to the length of the infiltration path. The constant of the leaching rate of K and the time required from full leachingout of K to its entrance into the liquid phase were obtained according to the experimental data. When the infiltration rate increased from 0.159 to 0.318 m/h, the leaching rate constants were 0.03132 h-1 and 0.04383 h-1 respectively; the time required from the full extraction of metal ions to their entrance into the liquid phase decreased from 297.528 to 218.997 h. Insitu leaching mining of deeply buried polyhalite can alleviate severe shortages of potash resources in China.