Abstract: TheYinggehai basin is located in the juncture area between Indo-China continental block and northern continental margin of the South China Sea. Dynamic mechanism for generation and evolution of the Yinggehai basin has become the debating focus due to its complicated tectonic setting. This paper analyzed the high resolution seismic reflection profiles in this area, and calculated the stretching factor of the upper-crust, crust and lithosphere, using the forward modeling software STRETCH and backstripping modeling software FLEX-DECOMP, suppose the stretch was depth-dependent, the β-factor of upper-crust is between 1~1.26, the β-factor of the whole crust is between 1.1~2.3, and the β-factor of the whole lithosphere is between 1.1~4.