College of Geo-exploration Science and Technology��Jilin University��Changchun 130026��China

In order to solve the instability problem of downward continuation in calculating normalized full gradient of gravity anomalies��we take the regularization factor into downward continuation and propose a method of calculating normalized full gradient of gravity anomalies based on regularization method�� In the modal test��we test- ed and analyzed oil-gas reservoir of the inhomogeneous sphere-coronal modal with different thickness�� The result shows: with suitable harmonic wave number and the regularization factor��the characteristics of“one less value and between two high values”can be well identified��and the identified ability is better than with routine fourier trans- form�� The fact indicates that the method can enhance the stability and the resolution of anomaly in calculation re- sult�� In application��the method not only showed the position of the known oil-gas reservoir��but also prospected five oil-gas areas��