Abstract: This paper reports the changes of ultrastructure and some cvtochemical contains(PAS,Sudan Black B,Acid phosphatase,Alkaline phosphatase,α-naphthyl acatateesterase,Peroxidase)in the development of the haematic cells of kidney and spleen in thegrass carp,Ctenopharyngodon idella,The characters and ways of haematopoiesis,and therelationships between these changes and functions ofhaematiceells have been discussed.The haematopoietic matrix cells of kidney and spleen in the grass capo include threetypes of cells:fibrocytes which can be devided into active fibroblasts and inactionfibrocytes,reticular cells and endothelium cells of blood capillary,The latter two types ofcells can be devided into phagocytosis and non-phagocytosis types.A preliminary investigation was made on the functions of the haematopoietic matrix cells and themicroenvironment of haematopoiesis.