This paper presents a method for simulating basic manufacturing operations (unload, load, process, move, and store) in a 3D virtual environment. The virtual environment provides a framework for representing a facility layout in 3D, which encapsulates the static and the dynamic behavior of the manufacturing system. The 3D manufacturing objects in the facility are mapped with the nodes in the framework. The framework, a modified scenegraph structure, is a tree structure, which can be manipulated by updating the parent-child relationships and the transformation matrix to simulate the basic manufacturing operations. The method can be easily extended to represent more specific manufacturing operations.