Effects of silicon on changes of glutathione peroxidase (GSH--Px) and superoxide dismatase (SOD) and peroxidase (POD) activity of Zizyphus jujuba cv. Jinsi-xiaozao of one-year-grafted seedings under salt stress were studied. The experimental results showed that superoxide dismatase (SOD)and GSH-Px activity increased with increased of salinity under salinity conditions, POD activity increased under 0.25G NaC1 and decreased under 0.4% NaC1. When siliconwas added to soil salt, S()D, POD and GSH--Px activity increased significantly. It was implied that the damage by salt stress on Z. jujuha cv. Jinsi-xiaozao could be alleviated by silicon.