研究顯示，大地震發生前幾天電離層之電子和離子濃度、溫度等會有變化，稱之為地震電離層前兆。本論文將利用盒鬚圖研究DEMETER衛星紀錄之電子濃度，電子溫度，離子濃度和離子溫度，還有全球電離層圖資料觀測2008年5月12日汶川地震電離層前兆現象，發現在汶川震央上空地震前1-6天晚間的電子濃度，離子濃度和日間的離子溫度與後1-6天比較有明顯負異常，而全電子含量在對應空間亦有負異常。進一步研究2005 - 2009年期間20個地震規模M≥7.5地震電離層前兆與DEMETER電子濃度和全球電離層圖之關係，結果顯示DEMETER有較佳空間解析度，但其資料時間解析度遠低於全球電離層圖，因此，整體而言全球電離層圖對地震電離層空間異常前兆之偵測能力較顯著。;This study observe seismo-electromagnetic anomalies by the French satellite DEMETER (Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions) during the 12 May 2008, magnitude 7.9 Wenchuan earthquake. The nighttime electron density (Ne), electron temperature (Te), ion density (Ni) and ion temperature (Ti) are investigated. A statistical analysis with the box-and-whisker method is applied to see if data of two or more groups under study are significantly different. A cross-examination of temporal variations before and after shows that Ne and Ni decreases appear 1–6 days before the earthquake. A comparison of data over the epicenter and those over its reference area can be employed to discriminate the earthquake-related anomalies from global effects. Results prove that anomalous enhancements of Ne and Ni occur specifically around the epicenter area. The intersection of the temporal and spatial results confirms that Ne and Ni are useful and sensitive detecting anomalous related to the 2008 M = 7.9 Wenchuan earthquake. Meanwhile, study the phenomenon of SIPs in 20 M>=7.5 earthquakes during the period from 2005 to 2009 by DEMETER electron density and GIM TEC data. The results illustrate that the DEMETER data by situ observation is more precise than GIM TEC data by remote sensing, but much difficult to find the phenomenon of SIPs.