The aim of the research is the achievement of conveniently applying the method of physic symmetric analysis in economic dynamic systems in order to uncover characteristics and evolving laws implied in economic dynamic systems.A unified framework which can be well adapted to describe a majority of dynamic economic models in mainstream economics by using the form of a kind of Lagrangian model was presented,and a so-called economic Vakonomic model was built.The feature of this framework is: the dynamic economic systems are endowed with a geometric structure by means of the mathematical method of differential manifold and symplectic structure,meanwhile some analogue between the economic dynamic systems and physic systems was established.