Abstract: The construction of new power systems has accelerated the evolution of the form, technology, and functions of the power grid, thus enriching the functions of power grid investment. It is therefore necessary to further understand the functional needs of power grid investment, optimize the investment structure, and further support the transformation of the energy and power structure. This paper uses the system dynamics model to study the changing trends of various forms of the source-grid-load power system during the construction of the new power systems, clarifies the evolution trend of power grid infrastructure investment during the construction of the new power systems, and studies the quantitative evaluation method for investment scale to form a power grid investment demand system that can meet both the needs of traditional economic and social development and the needs of new energy rapid development.