Abstract: Through the fine interpretation of high-resolution 3D seismic data collected from the slope area of the Lingshui Sag in the Qiongdongnan Basin, extensively developed mass transport deposits (MTDs) have been discovered with the characteristics as follows: (1) The mass transport deposits usually show weak amplitude, low continuity, chaotic or blank seismic reflection with obvious erosion; (2) A large number of internal structures such as erosional scratches, thrust nappe structures, and squeezed ridges are observed in the body and toe parts of the deposits; (3) Mass transport induced thrust nappe structures caused by internal structural deformation are common and the surface morphology of the deformation is always characterized by continuous protrusions and depressions. Two stages of MTDs, i.e. MTDs1 and MTDs2, are found in the study area together with associated turbidites. The ridges 10~15 km long and 2~3 km wide formed by the MTDs1may change the morphology of seafloor, block the way of later turbidity currents and change the location of turbidites.