Abstract: Using cucumber (Cucumis Sativus L.) as experimental material，we studied that the effect of exterior calcium on salt tolerance of cucumber seedling. The result showed that under 100 mmol•L-1NaCl, cucumber seedling biomass declined significantly, chlorophyll content and protective enzymes activities decreased significantly, lipid peroxidation index MDA content increased significantly, which leaded to growth inhibition. Exterior calcium could alleviate salt injury in certain extent, because plant biomass enhanced, chlorophyll content, SOD and POD activities increased significantly, MDA content decreased significantly, at the same time, free proline content rised significantly and osmotic adjustment ability strengthened. The effects were different due to different calcium levels, in which the effect of 40 mmol•L-1 CaCl2 was the best. Basing on the above result, it was indicated that a range of exterior calcium alleviated the inhibition of cucumber seedling under salt stress and induced salt tolerance.