Abstract: In order to develop a kind of the new inhibitor of low toxicity and high efficiency against TMV, the inhibitive effect of the new oligosaccharide Schiff base derivatives against TMV was conducted. The results showed that: (1) on Xanthi-NN, chitosan and its derivatives could all reduce the number of the dry spots infected by TMV effectively by screening potions with the dry spot host half leaf method, and the best result was obtained for salicylaldehyde chitosan Schiff base giving the inhibition rate of 66.39%; (2) on Nicotiana tabacum K326, chitosan and its derivatives can lower the decrease of chlorophyll content, and increase activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), polyphenol oxidase (PPO) and phenylalanine ammonia-lyase (PAL) in inoculated leaves, at the same time the content of proline had also accumulated.