In terms of the transmission network development case selection, there are deferent emphases for the development department, power dispatching and other departments, and evaluation indexes and methods in case selection of transmission network development are deferent to take, as a result it is difficult for the developing, scheduling and other departments of grid to form an objective, comprehensive, unified development scheme, and cause the contradiction among transmission network planning, construction, operation and other aspects. In order to solve the problems above, and make the grid planning, operation, construction and other departments evaluate the schemes of grid planning on the same platform, this paper presents a method to select an appropriate case of transmission network development planning based on adaptability and evidence theory. The concept of adaptability is established and characteristic path length, clustering coefficient, short-circuit current, maximum power flow of the line, net present value and other indicators are selected to quantitatively evaluate the degree of power grid development. Then the evidence theory is used to integrate the aspects of safety, economy and other adaptability indexes. The optional parameters are obtained to provide the basis for the selection of transmission network development planning. The method present in the paper solves the coordinate problem of transmission network development cases to select. Simulation of actual power grid development scheme selection shows the feasibility and validity of this method.