Improving carnallite quality by reducing impurity content is the fundamental guarantee to obtain high quality KCl products.In order to reduce the content of impurities and improve the quality of carnallite effectively，taking carnallite from Chaerhan Salt Lake as raw material，the impurity removal tests were carried out by using the combined process of pretreatment and reverse flotation.Pretreatment included proper grinding of the coarse particles≥1.25 mm was used to make its size less than 1.25 mm and removal of the fine particles <0.074 mm from was conducted the raw ore <1.25 mm.The particles size of less than 1.25 mm after grinding were combined with the particles size of 0.074 mm to less than 1.25 mm as reverse flotation feed.The process of reverse flotation was one-stage roughing and one-stage sweeping，the roughing concentrate was combined with the sweeping concentrate.The K⁺ grade of getting carnallite concentrate was 13.01%，the recovery was 98.24%，the content of w（Na⁺） was 1.45%，w（Ca²⁺） was 0.092%.The results showed that the direct reverse flotation was difficult to remove calcium impurities effectively，reducing the Ca²⁺ content of the concentrate to below 0.12%，and was easily affected by coarse particles during the flotation process，reducing the quality of the concentrate and potassium recovery rate.Compared with the reverse flotation，using the pretreatment combined with reverse flotation，the removal rate of sodium and calcium impurities was increased by 4.98% and 28.08%，respectively.The Na⁺ and Ca²⁺ contents of the concentrate

were lower，especially the Ca²⁺ content could be reduced to less than 0.12%，the concentrate quality could meet the requirements of high quality carnallite.It could provide material guarantee for the follow-up production of high quality KCl products.