Based on the study of the slope model for gravity and magnetic corresponding analysis,the authors point out that the magnetism-density ratio can effectively determine the lithologic boundary of the geological body.This method was first used in northeastern region of Tibet,the satellite gravity and magnetic data were used to analyze the magnetism-density ratio attribute of deep crust fractures in this region,and the result was verified by seismic data obtained by previous researchers.It is shown that there exists very good corresponding relationship between the magnetism-density ratio and the lithologic transfer interface.