Abstract: From the perspective of multi-body system dynamics, this paper systematically expounds and summarizes the universality of the source of law, the universality of complex system, the applicability of modeling and solving, and the materiality of the research object for the principle of virtual power. In accordance of the law of conservation of energy, the relation among the principle of virtual power, the law of kinetic energy and Newton's law is explained. Combining the characteristics of geometric nonlinear beam and pulley rope system with dual properties of both solid and fluid, some new ideas on the principle of virtual power are discussed. This paper is helpful to deepen the understanding of the virtual power principle, and it is also expected to provide a theoretical reference for the modeling and solving of complex multi-body systems with different forms.