This paper describes the morphology and organization of the brain of eight freshwater cyprinids by whic inhabit in different layers of water.The brains of cyprinidsfishes have no obvious difference, except the medulla oblongata. The differennes morphology and organir.tion in the brain a cyprinids not quite depend on thetaotogical system 'but to a great extent on their eeoenviranment and habit.Therefore, the differences have no ificance to be taken as the distinctive Featurein classification. The brain of the fish with the same habit has more similaritiesmorphology and organization.