Cucumber was cultured in open-top CO2 controlled chambers to study the interactive effects of elevated CO2 and potassium (K) on soil quality chemical properties. The results indicated that N and P nutrient contents in soil decreased at elevated CO2 and higher K supply, and K nutrient content increased with the increase of K supply. Higher K supply （200 and 300 mg/kg）and elevated CO2 reduced NO3-, PO43-, Ca2+ and Mg2+ contents in soil. Therefore, in the future elevated environment higher K supply can improve the nutrient uptakes of crop from secondary salinity soil and reduce salt ions accumulation.