Abstract: Using the Strept Avidin Biotin-peroxidase Comple x(S. ABC) immunocytochemical staining technique,the immunoreactive endocrine cells in the brain,pituitary gland and ovary of oriental sheatfish(S. asotus) and ye llow catfish(P.fulvidraco) in maturity and immaturity were locatized with 2 kinds of antisera-gonadotropin releasing hormone(GnRH) and gonadotropin releasing hormone receptor(GnRHR).The result showed that there were GnRH and GnRHR immu noreactive endocrine cells in the brain,pituitary gland and ovary ofS. asotus andP. fulvidraco.The GnRH and GnRHR immunoreactive cells are more and th e immunoreactive intensity is higher in the hypothalamus,pituitary and ovary of both fish in maturity than in immaturity.There are no change of GnRH and GnRHR positive reactive substance in the telencephalon,midbrain,spinal bulb and cerebellum in maturity and immaturity.The positive neuron and neurofibrae are more in th e hypothalamus of both fish in maturity than in immaturity. GnRH immunoreactive neuron show dark brown in color and their cell nucleus are light color.The shape of GnRH immunoreactive neuron is variform,they show shuttle,oval and triangle i n shape.Most of the have one or two long cytoplasmic processes.The GnRH immunore active neurofibrae are dark brown in color and in the shape of string beads.This paper discussed that the possible physiological function and morphological evid ence of GnRH and GnRHR regulated directly or indirectly the development of gonad on S. asotusandP. fulvidraco.It provided new morphological basis for the research field of hypothalamus-pituitary-gonad axis,neuro-endocrine and th e functional diversity of GnRH.