Abstract: There are a few of articles about fibrins of skin wounds observed by SEM.Fihrins is a sign of diagnosing antemortem injury,and has a resistance to the effect of water for a long time.But it is not clear whether fibrin networks can also be formed or not on the skin wounds surfaces in water.So skin incised wounds were made on SD rats in water before death,and the wound surfaces were observed by SEM.The authors found that there was not fibrin networks on the wound surfaces.Comparing with the results of skin postmortem wounds could not distinguish antemortem injury from postmortem injury. But the authors also found that the wound surfaces made before death and then put into water co- vered with a layer of fibrin networks.