Objective To improve the rat model of diffuse brain injury and establish a simple and practical animal model to study closed diffuse brain injury． Methods The marmarou-brain injury model was improved． The morphological changes of brain injury was detected by routine histochemical and silver staining． Ｒesults In the improved rat model diffuse heamorrhage were observed． Which included bleeding，swelling of nerve cells，glial cells eosinophilic change，loose brain tissue，nerve cell degeneration and necrosis，perineural phenomenon． Conclusions The improved marmarou-rat model could be used to study closed diffuse brain injury．