According to the new 3D seismic data, three seismic identifications of natural gas hydrate are discovered in south of Xisha Islands seas, South China Sea: (1) Obvious bot om simulating reflector (BSR) shows strong amplitude and continuous reflection, opposite polarity in contrast to the seafloor reflection, and nearly paral el to sea floor and translayer phenomena. (2) There are blanking zones(BZ) accompanied with BSR. (3) Amplitude enhances versus increasing offset. Natural gas hydrate distributes in dispersive blocks in plane and gas hydrate enriches in center but gets reducing toward periphery within a single block. It is estimated that the stable zone of gas hydrate is about 120m thick. The result of geology analogy shows that gas hydrate accumulation is commonly effected by some conditions in-cluding gas source, temperature-pressure and structure-sedimentation. A geological model of gas hydrate accumu-lation is established.