Abstract: The disadvantaged factor, such as deep-seated reservoir, worse rock petro-physical property, longer survey line and well data incomplete, results to the weak seismic reflection and lower seismic resolution in late Mesozoic. Therefore, it is hard to make a study on reservoir characterization in this area. In this paper, 2D seismic impedance inversion for late Mesozoic interval has been executed in the south ECS area. The results of inversion show that upper basalt and lower glutenite reservoir concentrated in the structure SE in K₁-K₂ strata, in the middle of which is dominated by thin alternating layers of sandstone and mudstone; better petro-physical property reservoir in J₁ strata, thin and tight sandstone reservoir in J₂-J₃ strata.