Abstract: The mechanical models in the mechanics curriculum system, such as particle, rigid body, deformable body, ideal fluids, etc., are scattered across different courses, and their interrelationships are rarely discussed. In response to this issue, this article elaborates on the evolution path from the basic mass particle model to the mass particle system, rigid body, continuum, and then to the multi-field coupling model, and explains the logical correlation between different models as well as the conditions that a "good" mechanical model needs to meet. The discussion helps ones to see the forest and the trees in the knowledge system of mechanics.