Abstract: In order to better understand the lithospheric extension process of the Qiongdongnan Basin, lithospheric stretching factors were calculated along the Line 1 which across both the continental shelf and slope. Upper-crust stretching factors were calculated by summing heaves measured on seismically imaged faults, varying from 1.678~2.238. Whole crust stretching factors changed from 1.251~2.468, derived from crustal-thinning constrained by seismic reflection and gravity inversion. Lithosphere stretching factors were determined from the combination of the two-dimensional flexural-cantilever forward and reverse modeling, ranging from 1.062~2.647. The results indicate that the depth dependent model is likely optional in the Qiongdongnan Basin. But the stretch factors are not simply increasing with depth, but also related to rheological features and the anisotropy of lithosphere before stretching.