To adapt to the uncertainties under the future energy structure change, the power system transformation elements on the energy side, load side and grid side are analyzed and composed. And then, the concept of carrying capacity is proposed and conducted from three perspectives: the definition, the assessment indicators and how the indicators guide the planning. The proposed carrying capacity indicators are embedded into the grid planning model in the form of objective functions or constraints. In the final, the Garver-18 nodes test system is applied to verify the correctness and validity of the indicators and the planning model.