Presented in this thesis is the virtual factory simulator (VFS) as a 3D solid-based factory simulator for the design evaluation of an automated manufacturing system (AMS), in which the target AMS is modeled employing an object-oriented graphical modeling framework, called JR-net (job-resource relation network). For developing the VFS, we propose a model conversion approach, in which the target AMS is modeled employing a 3D JR-net and this input JR-net model is systematically converted to a DEVS (discrete event system specification) model. For this purpose, the JR-net modeling framework has been extended further to handle 3D geometric information while providing a formal specification of the JR-net. Also a hierarchical DEVS model architecture and a systematic conversion method for converting a JR-net model into a DEVS model are proposed. Based on the proposed approach, a 3D-based VFS has been developed in C++ with OpenGL and a DEVS engine. The developed VFS may be used as a virtual prototyping tool for designing new AMS. Its validity is demonstrated by applying it in constructing a virtual factory of a special type of AMS called FMS (flexible manufacturing system).