Abstract: The obvious anomalies of gravity field in the northern South Yellow Sea distribute in a gradient belt form, which reflects the main geological characteristics of structural framework with uplifts, depressions and faults in this area. The main structural framework of South Yellow Sea consists of NE-trending faults, and Jiashan-Xiangshui fault belt and north margin of South Yellow Sea fault belt formed the south boundary of Su-Lu orogenic belt together. The aeromagnetic and gravity data indicate that the Gongjiadao NW-trending deep fault, a new discovery, controls basement formation and magmatic rocks distribution in the northern South Yellow Sea. The Precambrian crystalline basement exists in northeast sag of northern depression in the South Yellow Sea from inversion and interpretation of magnetic and gravity data. The aero gravity data indicate that Jiaolai basin extends eastward into South Yellow Sea with maximum thickness of deposition up to 3 km. These new recognition and discovery can provide some solutions for further investigation of marine regional geology, oil-gas investigation, and other fundamental geological problems in the northern South Yellow Sea.