中文摘要：

基于中国地壳运动观测网络的GPS观测数据，解算得到了汶川Ms8．0地震前中国区域上空电离层TEC分布图。用两种方法的研究显示，在相同时间和空间电离层TEC存在显著的异常扰动，即震前1～6天（除5月9日电离层TEC出现异常增加外）时间内多次出现显著的TEC异常减少，而且电离层TEC的异常驼峰有向磁赤道漂移的趋势，由于距离发震时刻较近，排除其他因素后认为该异常可能源于汶川Ms8．0地震引起的电离层效应。

英文摘要：

An Ms8.0 earthquake struck Wenchuan in Sichuan province on May 12th 2008 and had resulted in severe damage. On the basis of the GPS observation data from the reference stations of Crustal Movement Observational Network of China, the continuous 31 day TEC values over whole China were computed, examined and compared with two statistical analysis method, both the results showed that the ionospheric TEC anomaly did exist 1 -6 clays prior to the earthquake in the region, the apparent anomalous reduction of TEC occurred on most of these days except the May 9^th on which the TEC value anomalously increase evidently, and it was also shown that the anomalous crest of the TEC moved toward equator. Seeing the time was close to the moment when the earthquake occurred, it can be concluded that the existent ionospheric anomaly is possibly related to the earthquake after excluding all the other possible factors.