Abstract: In this paper, with Akshabulak sub-sag of South Tuergai basin as an example, a brief introduction has been made on 3D structure evolution analysis and its application to target optimization in deep fault block of rift basin. The structural characteristics of study area can not be reflected fully with conventional 2D structure evolution analysis. Through 3D structure evolution analysis, this shortcoming can been overcome. The structural characteristics of the study area in different geological period can be understood comprehensively. Combined with understanding about source rock and hydrocarbon accumulation, it has been made clearly that the positive inversion structural belt in the southern part of the study area is the most favorable area for the next exploration, and the fault block traps are the most favorable exploration targets for the future.