According to exploration seismic sounding data,density stratification wag fixed forgravity anomalies along the Fenghuang-Chaling geoscieroe section.The section density model wasessablished with the help of variable density horizontal trapezoid body,ac th6 calculated theoretical anomalies are coincideal with the measured Bouguer gravity anomalies.The Bouguer gravity anomalies can be reasonably interpred on the basis of the section density model.The earth crust was divided also sedimentary cover, metamorphic layer aam gramlito layer,with the gravity effect curves of these three layers and the gravity effect curve of the upper mantle low densitybody calculated respectively.In addition,the gravity anomaly curve caused by MOho reliefwas calculated, and various factors aam characteristics that give rise to crustal gravity anomalieswere analysed.