Abstract: Diplostomum niedashui Pan et wang and Diplostomum hupensis Pan et Wang infect the fry of Hypophthalmichthys molitrix, Aristichthys nobilis, Ctenpharyngoden idella, Cirrhina mo-litorella and other freshwater fishes, earning high mortality among fishes in Pisciculture. The freshwater gastropod, Radix swinhoei (H. Adams), is the first intermediate host of the two species, as observed both in the laboratory and in the field. The second intermediate host includes many cyprinids and others such as P. dabryanus Sau., Gambusia affinis (Baird Gir), Monopterus albus (Zuiew), Tilapia mossambica Peters, etc., The definitive host is Larus ridibundus ridibundus L.