The gravity data from the sea region to the west of 124° E of the South Yellow Sea have been processed and the feature of gravity fields analyzed. An experience relationship formula on the filter wavelength and corresponding depth has been put forward. Combined with the geological and seismic data, the deep tectonic framework and structural characters as well as possible favourable prospecting district for hydrocarbon in the South Yellow Sea have been discussed and analyzed. The gravity data from the sea region to the west of 124 ° E of the South Yellow Sea have been processed and the feature of gravity fields analyzed. An experience relationship formula on the filter wavelength and corresponding depth has been put forward. and seismic data, the deep tectonic framework and structural characters as well as possible favourable prospecting district for hydrocarbon in the South Yellow Sea have been discussed and analyzed.