In this paper, we establish the yoyo structure for each general system. Analogous to the important role of Euclidean spaces in modern science, the introduction of this yoyo model makes the research of systems science possess its very own intuition, system of methods and logic of thinking, which provides a methodological guarantee for the further development of systems science. After we justify the appearance and existence of such a model, we apply this model to generalizing Newton's laws of motion for the purpose of being able to apply these laws equally in natural and social sciences.