The subduction of the Paleo-Pacific and Philippine plates generates large-scale magmatism and crustal thinning in southeastern (SE) China. However, the dynamic process for crustal thinning in this region is still not well understood. In this study, a large number of receiver function data were used to investigate the crustal thickness and Vp/Vs ratio beneath SE China by the H-κ stacking technique. We also apply a comprehensive analysis method on the Moho Ps converted wave in radial and transverse receiver functions to calculate crustal seismic anisotropy with fast polarization direction and splitting time. The measured results show that the high Vp/Vs ratio (∼1.85) was mainly spread around two areas, forming a “V-shaped” zone. The western branch of the “V-shaped” zone was NS-oriented with a thin crustal thickness of ∼29.1 km beneath the Nanxiang-Jianghan basin. The eastern branch extended along the Tanlu fault with a thin crustal thickness of ∼28.8 km. Moreover, the measured crustal seismic anisotropy also shows that most stations located near the “V-shaped” zone exhibit significant crustal anisotropy with splitting times of 0.20–0.72 s. The fast directions of these stations are parallel to the direction of the V-shaped extension. Combining the geological data, we propose that the “hot fingers” may grow from mantle corner flow in the southern part of the V-shaped zone associated with the collision of the Pacific and Philippine plates. We deduce that the V-shaped crustal thinning and Moho uplift in SE China might be attributed to this mantle corner flow.