Abstract: The slope break of the Lingshui Sag in the southeastern Qiongnan Basin is characterized by complicated topographic and geomorphological features on seabed and structural deformations in middle and deep parts, that leads to the low precision of seismic velocity models in this area.The quality of images is seriously affected as the result. In order to build an accurate velocity model for the area, this paper for the first time used an integrated method, which includes multiple attenuation, broadband processing, pre-stack signal-to-noise ratio enhancement and other specific processing techniques, to obtain a broadband high signal-to-noise ratio pre-stack data set.The initial velocity model of pre-stack depth migration is then established on this basis by using velocity statistics and trend constrained modeling techniques.High-resolution grid tomographic inversion technique based on broadband data is used to establish the optimal high-precision velocity model. Finally high-precision prestack depth migration imaging is realized. The pre-stack depth migration profile based on the velocity model shows that the technology of pre-stack depth migration based on the fine velocity model can obviously improve the signal-to-noise ratio in the slope break area and the imaging quality, and effectively eliminate the formation coaxial distortion. The true structures of underground strata are reconstructed, which may provide more reliable seismic data for target evaluation and drilling decision-making.