Abstract: In order to improve the inhibition of saline alkali soil on crop growth in Daqing and promote the breeding of salt tolerant maize varieties,with maize Longyu 4as the material,maize seedlings were treated with NaCl stress and alleviated by adding(1,3and 5mmol·L^-1)concentrations of Ca²⁺,and the contents of malondialdehyde（MDA）,chlorophyll,peroxidase （POD）,soluble sugar,soluble protein and proline were measured.The results showed that the plant under salt stress compared with the control indicated the MDA content increased,chlorophyll content decreased,POD activity increased and soluble sugar content increased,significant differences（P＜0.05）.Proline and the content of soluble protein increased,but the differences were not significant.After adding 3mmol·L^-1 Ca²⁺,the contents of MDA,proline,soluble protein and POD activity decreased to the lowest level compared with salt stress group,and the differences were significant（P＜0.05）.In conclusion,exogenous Ca²⁺has a certain alleviating effect on maize seedlings under salt stress,and 3mmol·L^-1 Ca²⁺treatment has the best alleviating effect on maize seedlings under salt stress.