<p>The oilfield brine located in the western part of the Qaidam Basin in Qinghai Province has a high degree of mineralization, abundant reserves, and is rich in high-grade elements such as lithium, potassium, boron, and bromine, possessing high development and utilization value. This paper conducted a summer evaporation experiment on the chloride-type oilfield brine within the Nan Yishan structure in the Chaixi area, and obtained the evaporation and crystallization sequence of the brine, the enrichment patterns of elements, and the loss of elements at each stage under natural conditions. The experimental results are as follows: (1) The salt precipitation rule under natural conditions is: Halite → Sylvite → Carnallite → Antarcticite ; (2) The overall enrichment pattern of elements is: as the evaporation rate increases, potassium, sodium, calcium, magnesium and boron become enriched in the brine solution, eventually precipitating in the solid phase upon reaching the corresponding stage; whereas bromine and lithium continue to accumulate in the brine solution without undergoing solid-phase precipitation, and the enrichment multiple of lithium in the final stage is 26.3 times, with a maximum concentration of 5.26&#xa0;g per liter; (3) The study found that during the evaporation process, lithium and potassium lose with different degrees of loss, which should take into account the entrainment of the solid-liquid entrainment loss in the solid phase and the loss of irregular crystal structure or mineral adsorption during different stages of salinization. Moreover, the loss rate increases with the increase of evaporation loss rate. Overall, oilfield brines are expected to serve as a potential subsequent supplement for lithium and potassium resources, and the experimental results of this study can provide a fundamental data support for their future industrial utilization and production practice.</p>