Engineering design and planning activities decide on engineering objects according to intent of the responsible humans. In the other hand, advanced computer models are applied for analysis of behaviors of the modeled objects. The paper introduces a method for design intent based behavior modeling of mechanical products. Environment adaptive model objects apply embedded, integrated, or referred knowledge representations for the description of design intent. Behaviors of the modeled engineering objects are simulated for typical circumstances. Results of simulation are evaluated then applied at modification of environment adaptive product model objects. In this way, design intent controls creation and modification of product model objects. The paper starts with an introduction into the role of design intent in engineering, with special emphasis on modeling of products. Following this, a multilevel model is conceptualized based on knowledge carried human intent. Next application of human intent in modeling is discussed and an intelligent modeling by environment adaptive model objects is proposed. Finally, implementation of the proposed method in recent modeling is discussed.