Abstract：In seismic exploration, subsurface salt dome, as a high-velocity geologic body, brought about aseries of problems to ordinary processing in timedomain and interpretation, for example, false imageof subsalt structure and abnormal stack velocityfield.Taking 3-D exploration in Precaspian Sea ofKazakhstan as an example, and through the analy-sis of models, real cases of seismic data in offshoresalt-developed zone of Mexico Bay as well as con-Crete analysis of its data, the paper firmly believedthe abnormal high-velocity salt body is the basicreason leading the subsalt velocity field to abnor-mal in the region. In the processing in the time do-main, the phenomenon of lower velocity in subsaltstructure is normal geophysical phenomenon,and isalso unsolved issue for the processing in time do-main. Currently, the more practical solution is todiminish the subsalt velocity abnormal issue byprestack depth migration, so that the true under-ground structural feature can be obtained.
