World wide survey has shown that shoals are common bed forms on the world continental shelf area. Work of past decades also shows that shoals on China Sea continental shelves are in a dynamic equilibrium with the current oceanography condition and are believed to be of a current tidal deposit regime. However, based on seismic data, this paper reports a non-current tidal shelf shoal on northern South China Sea Shelf – the Nanbeiwei Shoal which including Nanwei Shoal, Beiwei Shoal, Lufeng Shoal and Huizhou Shoal. The seismic results show that Nanwei shoal, Beiwei shoal and Huizhou shoal are all tectonic structure and are all dispir related. There is a thrust structure under Nanbeiwei Shoal. Several dispirs gestated on this thrust structure and some of them intruded upward to the sea bed and formed the Nanwei shoal, Beiwei shoal and Huizhou shoal. Those dispirs confined within an area of 50 km in diameter and formed a dispir system named Nanbeiwei shoal diapir system. Based on seismic profile interpretation, the paper believed that the development of the Nanbeiwei shoal diapir system was after the development of Dongsha uplift. Due to the development of the Nanbeiwei shoal system, a reservoir belt which favorite for the deposition of oil and gas was formed and also the oil/gas migration system was re-active. Both the potential difference and potential gradient of oil/gas migration driven force was created by the formation of the Nanbeiwei shoal diaper system. So the reservoir belt sounded the Nanbeiwei shoal diaper system by this paper will be a higher priority area for future oil exploration and the Nanbeiwei shoal diapir system itself will be a higher priority area for future gas exploration.