Abstract: This paper systematically summarizes the technical method of 3D geologic modeling with -medium scale (1:250 000) deep geological survey. Based on the service platform of MapGIS, database technology of DGSS and 3D visualization technology of CREATAR, the technical method of 3D geologic modeling with medium scale, and its visualization are realized. Adopting 3D visualization technology, on the basis of 2D geological survey result, synthesizing the multi-information about geology and geophysics, the 3D model of geologic structure is inferred and constructed, which can reveal the distribution and interrelation of various geologic bodies and geological phenomenon in certain depth underground. This method will offer technical support for the effective geological research and petroliferous basin forecasting.