A dynamic geological modeling method based on topology reasoning among sections is presented in this paper in order to resolve the geological section correspondence problems，which results in the bottlenecks of automatic modeling，and enables the 3D stratified geological solid model to be updated dynamically.With topology relationship construction and reasoning on the three-dimensional surface，this method increased the dimensions of the geological section correspondence，and implemented dynamic three-dimensional geological modeling.This method had been used in Nanjing urban geologic three-dimensional modeling.The result indicated that it was suitable for many kinds of section data，and enhanced the three-dimensional modeling efficiency.