Different from the traditional subtractive manufacturing, additive manufacturing - a more flexible and material saving manufacturing technology has been developed in these recent years. This paper presents a simulation and optimization framework for Additive Manufacturing (AM) processes in practical industry. Starting from multi-level part design, to process optimization and planning, from energy and material consumption to the Key Performance Indicator (KPI) evaluation, the paper presents a complete practical working flow of AM technologies. Four models are developed within the framework: the design model, the process optimization and planning model, the energy and material consumption model and the production model. All the four models connect subsequently one another. Their concepts and corresponding methods will be presented in order in each chapter of the paper. A close optimization loop can be formed by these models. The feedbacks of each model will be used to optimize the design as well as the process planning. Preliminary experiments data are generalized and analysed by each model.