Abstract: The large-scale development of renewable energy such as wind power and so on brings new challenges such as the difficulty of accommodation, etc., through the renovation of thermal power flexibility the flexible adjustment capability of power grid can be enhanced and the accommodation space of renewable energy can be elevated, meanwhile it needs to consider the economy of thermal power flexibility renovation and its influence on the accommodation of renewable energy. Therefore comprehensively considering conventional operating cost of thermal power units and all the increased costs after the flexibility renovation and combining with the carbon emission cost and wind curtailment cost, an optimal dispatching model before and after the renovation of thermal power flexibility, in which the minimized total cost was taken as the object, was established, and by use of comparison difference method the cost of the renewable energy accommodation system based on the renovation of thermal power flexibility was calculated. In the computing example, the established model was applied to such unit operating conditions as before and after the flexibility renovation, under different carbon emission intensities, whether considering the unit operating conditions under different schemes such as wind curtailment and so on and the cost size of accommodation system, and the relation curve of the renewable energy permeability with the cost of accommodation system was obtained by fitting, thus the effectiveness of the established model is verified.