In this paper, sudden anomalies of impending earthquake and obvious trend anomalies are analyzed statistically for eleven earthquakes(M ≥ 7.0) from 1969 to 1900 in China. The whole characteristics of sudden anomalies before the megaseisms, the distributing rules of the item-and-frequency with time(the interval from the sudden change date to the earthquake occurrence date), the synthetic distinguishing method of imminent anomalies etc. are discussed. The synthetie indices of imminent prediction for great earthquakes and the effectiveness of time prediction are further discussed.