For the intention that students can better grasp the related knowledge about NC technology,understand the use and operation of NC equipment,get familiar with the NC programming,the author researched a NC machining simulation system.Using Visual Studio 2008 as a development tool,combining the advantages of the three-dimensional graphics library-OpenGL and VC,introducing the object-oriented technology,using visualization and object-oriented programming method,we developed a three-dimensional graphic teaching simulation system with windows interface support suitable for NC machining.