Presented in the paper is a virtual factory simulator (VFS) framework as a 3D solid-based factory simulator to be used as a line prototyping tool for an AMS (automated manufacturing system). The VFS framework supports a 3D resource & factory layout modeling, a physical emulation, and a performance simulation: the physical emulation is used for the kinematics simulation, interference check between resources, and the generation & verification of device program; and the performance simulation is used for the material flow & control logic evaluation and system performance evaluation. The proposed VFS framework supports a fully integrated graphical modeling environment for emulation scenario modeling and material flow & control logic modeling. Therefore, the proposed VFS meets the modeling requirements of high modeling power, ease of model building & validation, and ease of communication with stakeholders compared to other commercial system. Based on the VFS framework, a virtual factory simulator named VM-Factory� has been developed in C++ with OpenGL and a DEVS engine, and its validity was demonstrated by applying it in constructing a virtual factory of an FMS (flexible manufacturing system).