The space time distribuion of the disastrous 1998 flood in the middle and lower reaches of the Yangtze River (MALROYR) as well as in the central and northern areas to the south of the Yangtze River is illustrated and the causes to the flood are analyzed. The paper also shows light to the scientific ground as well as technical experience for the successful prediction of the disaster. The prediction difficulty is also briefly discussed. The space time distribuion of the disastrous 1998 flood in the middle and lower reaches of the Yangtze River (MALROYR) as well as in the central and northern areas to the south of the Yangtze River is illustrated and the causes to the flood are analyzed. The paper also shows light to the scientific ground as well as technical experience for the successful prediction of the disaster. The prediction difficulty is also briefly discussed.