A pot experiment was conducted to investigate effects of applying molybdenum and selenium on antio-xidative defense system and osmotic-adjustment system of pakchoi cabbage under salt stress.The results showed that both Mo and combination of Mo and Se increased yield of pakchoi cabbage.Co-application of Mo and Se increased the capacity of pakchoi cabbage to eliminate active oxygen and increased the ability of osmotic-adjustment of pakchoi cabbage.Single Mo also increased the capacity of pakchoi cabbage to eliminate active oxygen and the ability of osmotic-adjustment of pakchoi cabbage.Single Se had a very small role in enhancing salt stress tolerance of pakchoi cabbage.Mo and Se had synergistic effects on increasing Mo and Se uptaking of pakchoi cabbage.Co-application of Mo and Se not only increased salt tolerance but also produced Se-enriched cabbage.