There are 10 reliable precursor anomalies prior to the Wenchuan earthquake were found in Chinese Earthquake Geothermal Network(CEGN)after checking the groundwater temperature data in 273 observed wells. The duration,amplitude and spatial distribution of these abnormities have obviously individuality,which causes that it is difficult to make an accurately prediction of three elements of the Wenchuan earthquake. However,some interesting scientific discoveries have been found,the 10 wells with abnormities are concentrated in the 1000km around the epicenter,the amplitude of these abnormities in several thousandths to several hundredths of degree,and the duration has short-term nature. In addition,we find the rule of duration that the longer distance between the epicenter to the well,the shorter the duration and vice versus. The probability in recording abnormities of artesian wells is much higher than the hydrostatic wells,but the dry wells also can record the abnormal information. Based on these analyses,we get the conclusion that the anomaly of water temperature depends on the well-aquifer system structure and the observed well location in water-unit.