Abstract: Low Velocity Layer (LVL) zones are commonly seen in South China and the Northern South China Sea (SCS) and pinch out towards the sea basin. It is indispensable to understand the cause of LVL pinch-out in order to disclose the origin and development of the SCS. This article summarized previous studies and compared the distribution of LVL in South China and the Northern SCS based on interpretation of seismic sections from related areas. The results suggest that large fault zones play key roles in LVL pinching out in the Northern SCS. LVL might release its heat along great fault zones, accelerate the process of consolidation of early fusion layer and at the same time make the LVL pinching out.