Abstract: The Gabon Basin is one of offshore basins in West Africa. The basin began to form in late Jurassic. The Lower Cretaceous Ezanga Formation is composed of gypsum, in which several salt domes with 30~400 m in thickness are locally developed. Because of great velocity difference between salt dome and its host rock, seismic reflection of the Presalt Gamba Formation is abnormal at the salt dome. This paper analyses the Presalt structural features by means of seismic forward modeling. The study shows that no matter the salt dome is big or small, salt dome can produce "pull-down" phenomena in the Presalt.