Abstract: On the basis of 1:200000 gravity and magnetic results in Haijiao-Qiantang area in the East China Sea, using wavelet analysis and all magnetic latitude variable inclination turning to the pole, the distribution of pre-Cenozoic layer and the petroleum resources are discussed. It is considered:here exist Mesozoic group and Paleozoic group;in the area where the depth of bottom boundary of sedimentary stratum is greater than 4500m, Jurassic dark mud rock maybe exist;the study method and technique are feasible and available, and can be widely used in the study of distribution of pre-Cenozoic layer and forecasting oil-gas perspective.