In the CAD software for highway and railway route selection design, it is absolutely necessary that the lamination pattern be filled in the route stratigraphic section. On the basis of studying the structure of AutoCAD drawing database, and on the drawing platform of AutoCAD 2007, the authors made a tentative discussion on the generation of filling boundaries, development of hatch pattern library and invoking of pattern, using Visual C++2005 compiling environment combined with library functions of ObjectARX. With these methods, we can accomplish automatic generation of closed field boundary and calling-filling of the hatch pattern.