An earthquake (5.3) occurred on November 23, 1984 in Lingwu county, Ningxia Hui Autonomous region (38°04, N, 106°13, E, H=14km, I=Ⅶ). It is the strongest shock in Yinchuan plain since 1962. In this paper, it was reported that the process of medium and short-term forecast of this earthquake and its major precursory science basis. The results demonstrate that it is entirely possible to do medium and short-term forecast before a moderate earthquake using the anomalous characteristics of Seismic pattern and other precursory anomaly phenomena under favorable condition, but it is fairly difficult to do imminent-term forecast just prior to a moderate earthquake at present.