Process modeling and simulation is a key requirement for improved design and quality control of the evolving composite manufacturing technology. However in order to effectively use the available simulation software in this field a thorough knowledge of mathematical modeling techniques and material science is required. This work explores the use and ramifications of the object-oriented modeling and design (OOD) methodology in developing flexible process simulators for composites processing. Specifically, we have developed an object-oriented based simulator that possesses the required flexibility to model a large class of composite materials processing operations. The flexibility of the simulation software is demonstrated by simulating two widely used composite manufacturing processes (i.e. injected pultrusion and autoclave curing). In addition, through these examples we have clearly demonstrated that the object-oriented framework greatly facilitates development of hi-fidelity process models with significantly less time, efrort and expertise than the conventional procedural coding approaches.