The black start of power grids is a complex process consisting of the startup
the dispatch and the operation of plants and power grids. For the dispatchers and operators
how to determine the startup paths and the closedloop points are the most difficult problems. In order to implement the quantitative analysis of the above problems
the transient energy function (TEF) is introduced into this domain and a novel auxiliary decision-making system is developed. The system has been successfully applied to several local power grids in South China. Two practical cases presented by the paper demonstrate the methodology of the proposed method.