Due to the problems such as high cost and high risk of equipment which were commonly found in current NC training and machining area, with the development of virtual reality and computer software technology, a feasible programme of virtual NC machining simulation system which based Open Inventor was brought forward. This paper expounded the software and hardware platforms of virtual NC machining simulation system and its architecture framework firstly. Then focused on the research on virtual scene mapping and model optimization, NC code compiler process, the simulation of moving behavior, and proposed the common programming model of an event handling. Finally, An initial prototype system was realized in Visual C++2003.