Abstract: Objective To study the changes of cat cerebral mircocirculation in early stage after craniocerebral gunshot wound in the hot and humid environment to provide laboratory evidence for clinical treatment of such wound. Methods Craniocere- bral gunshot wound was induced in 24 cats according to the method described by Carey with modifications, and the cats were placed in a cabin with environmental temperature and humidity of 25℃ and 50% (group A), and 35℃ and 85% (group B), respectively, to observe the changes in all the indices of cerebral microcirculation. Results All the cats survived and notable changes occurred in the morphology and permeability of cerebral microvascular along with obvious pathological changes in the brain tissue, and the vital signs, hemorheology and blood-brain barrier were significantly different between groups A and B. Conclusion Hot and humid environment induces obvious changes in cat cerebral microcirculation and blood-brain barrier function in the early stages after craniocerebral gunshot wound.