Aim To study the changes of the biological behavior of dermal fibroblasts in Ⅲ skin burns wound in rats using chitosan.Methods Wistar rats were randomly divided into 5 groups as follows:1% chitosan(W/V)group,2% chitosan(W/V)group,4% chitosan(W/V)group,bFGF(basic fibroblast growth factor) group and the control group.Rats were made for Ⅲ skin burns.The wound healing time was recorded,and the wound healing rate was calculated.Then the cell cycle and apoptotic dermal fibroblasts were determined and the amount of Hydroxyproline(HOP) in the skin tissue was analyzed.Results The wound healing rate of 4% chitosan(W/V) group was higher and the wound healing time of 4% chitosan(W/V) group was shorter than that of the control group.On the 7th,14th day post-injury,the content of protein of 4% chitosan(W/V) group was higher than that of the control group.The content of HOP of 2% and 4% chitosan(W/V) group was highest on the 7th day post-injury. Compared with that in control group,the percentage of cells of S stage in 4% chitosan(W/V) group was aboundant,and was reduced in apoptotic dermal fibroblasts.Conclusion The changes of cellular biological behaviors might be one of the mechanisms of that Chitosan could promote the wound healing of Ⅲ skin burns in rats significantly.