The rhythm of multiplied nine days in different years is a method for predicting the occurrence of imminent earthquakes before they strike. It has the characteristic of counting to day clearly. In this paper, this method is used to discuss the occurrence date of the 1920 M_S8.5 Haiyuan earthquake. The results of this study can be used as a reference to predict the date of large earthquakes in Gansu and Ningxia areas from short impending time scale.