The factors influencing basic fibroblast growth factor (bFGF) to improve wound healing in severe burn were studied. Rats were subjected to 15% III degrees burn. The results showed that high activity of bFGF was maintained after escharectomy in early period. In treated group 84.0% of rats wound healing was observed on the 40th day, while it was 9.0% in control group. Heparin could enhance activity of bFGF to stimulate formation of granulation tissue, regeneration of capillary, proliferation of fibroblast and DNA synthesis. Control of infection was beneficial to preserve activity of bFGF. The authors believe that the proper time to use bFGF is one week after injury.