众所周知,在许多地震前可以观测到局部磁异常。选择位于中国最北部的国家级绝对地磁观测台内蒙古满洲里地磁台和黑龙江德都地磁台2008年的观测数据，采用差值法、响应比、能量比等分析方法，对2008年6月10日内蒙古阿荣旗M 5.2地震和7月7日黑龙江龙江县M 4.6地震前的局部空间磁场异常进行分析，并应用斜率分析和差分分析对差值法异常信息进行提取，发现在内蒙古阿荣旗M 5.2地震和黑龙江龙江县M 4.6地震前各方法均存在明显的异常，这些异常在一定程度上反映了台站周围小范围的震源区介质电性结构的变化。同时针对异常幅度、持续时间与地震强度间的关系进行了浅析。

It is well known that the local magnetic anomaly are observed before many earthquakes. We choose the absolute magnetic observatory data recorded by Manzhouli magnetic observatory in Inner Mongolia and Dedu magnetic observatory in Heilongjiang Province which located in the northern part of China in 2008. The local magnetic anomaly, before the MS 52 Arongqi earthquake in Inner Mongolian on June 10th and the MS 4.6 Longjiang earthquake in Heilongjiang Province on July 7th, are analyzed by differential method, such as response ratio and energy ratio method. We extract obvious abnormal information which has reflected electric property diversification of seismic source area around the two stations before earthquake by difference analysis and slope analysis method. In the end, we discussed about the relationship between the abnormal amplitude, duration and earthquake strength.