<p>Brine constitutes one of the primary sources of potassium (K), and the characteristics and genesis of potassium in brine are significant for the further exploration of potassium fertilizer. There is still little information about it in deep-buried brine. Fifty-eight deep-buried brine samples from the Dongying Depression were systematically sampled and analyzed to detect the characteristics and genesis of potassium. The samples have an average K⁺ level of 282.03&#xa0;mg/L (70.7–1652&#xa0;mg/L), which is lower than the minimum industrial grade. This region is dominantly characterized by a leaching-type brine primarily from hydrochemical evidence. The brine is lacking in Mg²⁺, Br^- and SO₄^2- and rich in Ca²⁺, Fe, Sr, Li and HCO₃^-. K⁺ levels in the brine are significantly positively correlated with TDS, Na⁺, Cl^-, Ca²⁺, SO₄^2-, Mg²⁺, Fe, Mn, V, Sr and Li, and negatively correlated with pH, indicating K⁺ accumulates in brine as evaporation and concentration intensify. Furthermore, the minerals of NaCl, CaSO₄ and SrSO₄ are undersaturated, and those of CaCO₃, CaMg(CO₃)₂ and SrCO₃ are oversaturated. The correlations of K⁺ with SI_NaCl, γCa²⁺ + γMg²⁺-γHCO₃^- and γSO₄^2--γNa⁺+γCl^- are observed, indicating the dissolution of halite and gypsum also contributes to K⁺ in the brine as isomorphous substitution. The low degree of evaporative concentration and the low K⁺ levels in halite and gypsum are responsible for the low K⁺ levels in the brines of the Dongying Depression. A possible conceptual model of potassium evolution in brine is put forward. This research provides some new insights into the further exploration of potassium in brine in the northern Dongying Depression and other regions worldwide.</p>