Paleocene-Eocene thick evaporites are developed in Kuqa depression, especially in the western part, with many salt spots. In this paper, the authors studied potash minerals and potassium-bearing salt minerals of Paleocene-Eocene evaporites so as to analyze potash-forming trend of Paleocene-Eocene evaporites in Kuqa depression. Glaserite mineral exists in potash-forming layer sectionⅠ; original sylvine, potassium gypsum and potassium-bearing halite gypsum occur in potash-forming layer section Ⅱ, indicating that ancient salt lake had reached potash deposition phase. Borehole chemical composition analysis shows that, from borehole bottom to the top, the shallower the depth, the higher the K⁺ concentration, with a maximum of 1.273%. In combination with characteristics of ions content, the potassium-to-chlorine ratio, the magnesium-to-chlorine ratio, the lithium-to-chlorine ratio and the strontium-to-calcium ratio, the authors determined two potash-forming trends during ancient salt lake evolution, and initially hold that potassium layer section Ⅰ and Ⅱ have the potential to form potash, with layer section Ⅱ having larger potential to form potash.