In order to further understand the tectonic evolution and mechanism of the Beibu Gulf Basin, this study analyzes the process of tectonic evolution of the basin and the mechanism of typical structure development using 2D/3D seismic, drilling and Bouguer gravity anomaly data. The results show that (1) the basin is characterized by two depressions and one rise, i.e. north depression, south depression and middle rise. The faults controlling the boundary of depressions in the Beibu Gulf Basin are large lowangle normal faults, separating metamorphic core complexes in footwall from hanging wall rocks. The metamorphic core complexes in footwall consist of the middle and highgrade ancient metamorphic rocks and the late magmatic rocks, such as kataclasite, breccia, mylonite and gneiss in mylonitic rockbearing shear zones. (2) A large inverted structure in the eastern part of Ushi depression was formed due to spreading detachment of faulting, superimposed by late stress rotation of the lowangle normal faults. (3) A formation mechanism of “Sandwich strata filling” mode is proposed for formation of bedding shearing strikeslip structure. The “Sandwich”mode flexible rocks occur as layers, which are subject to losing balance due to superposition effect of reversal tilting and late stress field rotation. Especially on the interfaces of the rigid or flexible rocks or within flexible interface exist distinct physical and mechanical difference, and the lower surface friction resistance of two- dimensional layered sliding surface can easily result in bedding shearing strike- slip.