In order to study the structural features of Yingen-Ejinaqi basin and provide foundations for further oil and gas resources investigation and evaluation, the characteristics and causes of gravity field have been discussed and analyzed, and the fault systems have been speculated through collecting, processing and studying the existing gravity survey data in the area. Regional gravity anomalies in study area are mainly aroused by the undulation of Moho surface. The basement faults divide the study area into multiple blocks, which made the Basin with the features of alternate sag and uplift.