Abstract: The aim of this study was to observe changes of caecal histological structure of rex rabbits and to summarize its law of development.Caecum was collected from six rex rabbits which were reared with the same feeding and management at 1,15,30 and 60 days old,respectively.Then the caecal structure was observed under a microscope after its paraffin section was stained by HE staining.The results indicated that the height of simple columnar epithelial cells and the size of goblet cells in cecum of rex rabbits increased with aging.The distance between two semi-duplicatures gradually decreased with aging.The length and volume of duplicatures also increased slightly with aging.In addition,the number of lymphoid nodules in caecal procussus vermiformis also increased greatly.The number of lymphoid nodules and disperse lymphoid tissue also became more and more with aging,and duplicature became intensive.