Abstract: Effects of silicon addition on chlorophyll fluorescence and gas exchange of Zizyphus jujuba cv. Jinsi-xiaozao under salt stress were studied by using 2-year-grafted seedlings. Ordinary agronomic soil was selected as pot-cultured medium. Sources of sodium and silicon for experiment were sodium chloride and potassium silicate. Soil salt contents (NaC1) were planned 3 levels,i, e. 0 g/kg,3. 0 g/kg and 5. 0 g/kg. Soil silicon (Si) contents were planned 2 levels,i, e. 0 g/kg and 0. 4 g/kg. The experimental results showed that the growth in soils containing 3. 0 g/kg or 5. 0 g/kg NaC1 for 135 d salt ions had distinctively negative effects on j isi jujube plants: Chlorophyll content decreased by 12. 30% and 22. 08% respectively compared with none-salt stress, while silicon addition increased chlorophyll content by 12. 30o//oo and 22. 08% respectively compared with under the two salt stresses;Fv/Fo and Fv/Fo of PSⅡ, two important chlorophyll fluorescence parameters,decreased by 19. 96%,34. 58% and 8. 86%, 14. 10% respectively, while increased 32. 25%, 30. 71% and 11. 26%, 12. 15% respectively under silicon addition; photosynthetic rate and cellular conductance decreased by 11. 04%, 25. 32% and 26. 13%, 16. 22% respectively, while increased 10. 94%, 20. 87% and 42. 68%, 10. 85% respectively under silicon addition. The results revealed the silicon addition ameliorated salt toxicity, osmotic stress and nutrition deficit on Z. jujuba cv. Jinsi-xiaozao plant under salt stress.