The failure have occurred many times at Wangxia dangerous rock in the history, to explore the reason of the frequency of dangerous rock failure in the area,  the authors assess different factors such as regional geological conditions,  rain and structure of the dangerous rock,  but also with deformation features of various sections of the dangerous rock and the monitoring data analysis. This paper indicates the origin and development of the dangerous rock is mainly dominated by the special geological environment and the free-face condition of the precipice slope, the continuous rainfall induced its re-occurring several times. According to the criterions of deformation and deformation velocity,  the dynamic track prediction about the time of the danger rock re-occurring will be prediction, a model was established for the special displacement of the experimental validation of some observation points,  and the prediction based on this model was achieved with high accuracy.