Abstract: Significant abnormal changes of water level in Huize well of Yunnan Provience were observed before several earthquakes, which indicates that the anomalies of water level in Huize well has good prediction efficiency to the earthquakes occurred surrounding the well. In this paper, the prediction efficiency of the water level in Huize well was tested by the Molchan diagram method, and the anomaly mechanism of water level was analyzed. The results show that the water level in Huize well has good prediction efficiency to earthquakes, and the anomalies can be used to predict the time and the site of the next earthquake. The prediction interval from anomaly appearance to next earthquake occurrence corresponds to three months, and the prediction area is the eastern part of Sichuan-Yunnan block. Because the Huize well was drilled in the junction of fault zones, water level in the well was sensitivity to the regional tectonic activity associated with the seismogenic process, which leads to the good prediction efficiency.