Effects of silicon (Si) on membrane fatty acid content, composition and fluidity in root and leaf of two-year old seedlings of Ziziphus jujuba cv. Jinsixiaozao under salt stress were studied. The results showed that the addition of Si had different effects on these parameters in root and leaf of the plant under NaCI stress: in root, the saturate fatty acid content decreased with added Si compared with that of no Si addition. Both the membrane unsaturate fatty acid content and the index of unsaturate fatty acid of the root were promoted under NaC1 stress with Si addition, but the effects of exogenous Si on membrane fatty acid (MFA) content and composition of the leaf were contrary to those of in root. The results from this study suggestes that Si regulates the content, composition and fluidity of Ziziphus jujuba cv. J insixiaozao under NaC1 stress, which is closely related to the physiological functions and growth characteristics of the plant organs.