As one of the biggest sea of continental margin in the west Pacific Ocean, South China Sea is one of the most important potential location where gas hydrate is expected be found.

　　Characterized with semi-close sea, the South China Sea has a total area of 350×104 km² with average water depth of over 1000 m and the deepest of 5377 m. In the South China Sea, the continental shelf is flat while the continental slope has a complicated terrain, which had provided sound geological environment for the formation of gas hydrate. With comprehensive analysis to the structure, sedimentation and climate after Miocene, it had been understood that the South China sea has sufficient gas generation, low sea bottom temperature (1-5 ℃) and moderate geothermal gradient (measured 14-76 ℃/km, average 35 ℃/km) which is ideal for the formation of gas hydrate. A serious of geophysical and geochemical observations had been identified to be evidences of gas hydrate concentration, such as bottom simulating reflect (BSR), decrease of chlorine ion concentration in pore water and abnormal methane content, which have indicated that this area can be a targeted area for gas hydrate exploitation in China.

　　The South China Sea has provided with sound sedimentation conditions for the formation of gas hydrate.

　　It has widely been regarded that gravity flow sediments, semi-pelagic (offshore) sediments, especially turbidity sediments are good reservoir for natural gas hydrate and the gravity flow deposits can basically meet the material requirement of natural gas hydrate. Due to the complexity of continental slope in the South China Sea, the depositional facies combination is suitable for gas hydrate.

　　The sand/mud ratio is another factor affecting the formation and accumulation of gas hydrate which could not be too low, not good for reservoir space, and could not be too high, negative for sealing, as well. The BSR study in this area has indicated that the sand/mud ratio is between 35%-55%, ideal for gas hydrate generation and accumulation.

　　The borehole investigation has revealed that the highest depositional velocity rate was found in Dongsha archipelago area, rated 87 cm/ka while this figure varies from 15-18 cm/ka in Holocene to 6-45 cm/ka in Pleistocene, which meet the requirement for the accumulation and formation of gas hydrate, according to the common understanding.

　　Sedimentation, structural and other geological setting have also provided in South China Sea a suitable place for generation, migration and accumulation of gas hydrate. It is predicted that gas hydrate accumulation could be found at a depth range between 300 to 2500 meters under sea level.

　　11 target areas in South China Sea have been identified based on this study where potentials gas hydrate resources could found. It is predicted that the gas hydrate reserves in this area accounts for approximately 50% of total natural gas reserves of onshore and offshore in China. It is recommended that instead of emphasizing only on sedimentation, comprehensive study on geophysics, geochemistry as well as hydro-dynamics in order to get a better understanding of this issue and be successful in the gas hydrate exploitation.