The Weddell Sea is the largest marginal sea in the Antarctic. Gravity and magnetic data,historical documents and the research products of tectonic evolution of the Weddell Sea have been comprehensively collected in order to describe the characteristics of magnetic and gravity fields and the opening history. In the north and central Weddell Sea, the gravity field is characterized by a dominant “herringbone” pattern of evenly spaced NW-SE trending fracture zones. A series of curving, concave up, predominantly east-west trending magnetic anomaly are lying on the Weddell Sea gravity herringbone. The continental shelf edge of the Weddell Sea is well marked by the prominent gravity anomaly high till the southern edge of the Weddell Sea. However, the magnetic anomaly is different in western edge and the southern edge of the Weddell Sea. The initial north-south rifting and opening of the proto-Weddell Sea has already occurred (150 Ma), then the transition to east-west spreading has occurred (140 Ma), African and South American system is well established in about 120 Ma. The spine of the Weddell herringbone of formed during that time.