Abstract: 1.Six 3-dialkylaminomethyl-6-nitro (6-acetamino-and 6-dimethylamino)-chromanones have been prepared for screening the therapeutic effect against Schistosomia Japonica in experimentally infected animals. 2.The Mannich reaction of the 6-nitro-chromanones was unsuccessful in literature cited.But we adopted three methods for the preparation of this compound and favorable results were obtained. 3.The preparation of 6-nitro,6-amino,6-acetamino and 6-dimethylamino- chromanones have been reported also.