Abstract: Mine geological condition is complicated. It can enhance the intelligentization of
mine design to adopt CAD. Some questions are studied, such as the method to draw the section
lines in the geological section plane and the geological plane graph intersected each other, the
principle and method of automatic determining ore body limits on transverse section by using of
the neural network theory, the one of drawing the slippery boundary of ore, and the method of
automatic calculation and statistics ore reserves and grade. A mine CAD system was exploited
with ObjectARX based on these methods. The experiment shows it is feasible and successful after
it was used in Beiminghe iron mine.

Key words: section line, ore grade, neural network, ObjectARX