The effects of potassium applied into soil on biomass yield, nutrient contents of winter jujube (Zizyphus jujuba Mill. cv. Zhanhua) and distribution of K+, Na+ in leaf and soil were studied by a pot experiment in order to explore the alleviation effect of potassium on NaCl stress of winter jujube and to provide a theoretical basis for rational potassium fertilization of winter jujube in the Yellow River delta. The results showed that the increment of fresh weight was significantly decreased by salt stress. The application of KCl effectively alleviated the inhibition of NaCl on winter jujube’s growth with a result of increasing leaf dry weight by 21.5%?–?29.8% under salt stress. The salt tolerance ability of winter jujube was enhanced from soil salt content of 2 g/kg to 3 g/kg. Also, the contents of N, P and K in leaf were increased and the nutritional status was improved. Applied K+ was beneficial in alleviating the injury of NaCl stress on winter jujube through enhancing K+/Na+ in leaf and reducing ion imbalance caused by salt stress to some extent. At the same time, chemical behavior of potassium in soil was significantly affected by salinity.