Abstract: The shale compaction curves from 99 wells in southeast slope of Dongying sag are studied in this paper, indicating that the shale compactions are characterized by transverse zonation and longitudinal segmentation. In transverse section, the shale undercompaction zone is distributed in Niuzhuang sub?sag and Wangjiagang slope transitional belt, in which salient zones are all normal compaction ones, while in longitudinal section, the compaction can be devided into the undercompaction segment in the lower part and the normal compaction segment in the upper part. The undercompaction segment is mainly distributed in the second, third and fourth members of Shahejie formation with depth of 1 900~3 800 m; the normal compaction segment is in the second member and overlying strata. Also, the calculated shale fluid pressure and the measured sand fluid pressure show that the formation fluid pressure in the southeast slope is of obvious zonation: by taking the top of the third member as boundary line, the normal pressure section occurs in shallow part, while the abnormal overpressure section occurs in deep part. And such a shale overpressure appears in wide lateral distribution with strong inheritance, and the area with excess pressure high value is located in the Niuzhuang sub?sag. The overpressure is basically the same with the shale undercompaction in distribution. The overpressure scale of sandstone is somewhat less than that of shale. The abnormal pressure in southeast slope in Dongying sag belongs to deposit overpressure, and the shale undercompaction is the main mechanism of it