Under the "dual carbon" goal, the large-scale grid connection of new energy poses great challenges to the safety and reliability of the power system. Faced with the goal of sustained growth in new energy, whether the carrying capacity of the power grid can meet the requirements, and how to evaluate the new energy consumption capacity have become key issues currently faced. In order to fully tap into the new energy consumption capacity of the power grid, improve computational efficiency and accuracy, this article first constructs an evaluation model for the new energy consumption capacity of the power grid; Then, taking into account the internal and external units of the target power grid, a new energy consumption capacity evaluation method based on unit regulation capacity constraints is proposed. The simulation results show that the proposed evaluation method can effectively evaluate the new energy consumption capacity of the power grid while ensuring the security constraints of the power grid.