Abstract: The effect of chitosan on seed germination and seedling growth. Treating the cotton seed with 0.5 g/L, 1 g/L, 1.5 g/L, 2 g/L, 2.5 g/L, 3 g/L of chitosan. The results showed that, when the concentration of chitosan reached 1.5 g/L, the germination rate increased by 16.56%, in the same time the seedling emergence time of cotton was 0.8 day earlier than the control group, and the emergence rate, plant height, fresh weight had increased by 15.53%, 11.85% and 9.63%, and the content of amylase, chlorophyll content, proline content, catalase activity had increased by 13.79%, 4.94%, 13.28% and 7.21%. Appropriate concentration of chitosan could promote seed germination and seedling growth of cotton and the promoting effect of the seed treated by 1.5 g/L was the highest. Above discussed in the paper providing a new insight into the application effects of chitosan in agriculture.