Abstract:With the increase of environmental pressure and the need of sustainable development,more and more renewable energy has been introduced into the power industry,which has brought great changes in China's power structure,and raised higher requirements for peak regulation of electricity.The trend and current situation of the development and change of China's power grid in recent years was analyzed and the flexibility modification technologies of the thermal power unit with deep peak adjustment were introduced.The difficulties in popularizing flexibility modification technology of thermal power units under the current ancillary electricity market rules were analyzed.Some suggestions on thermal power plants,power grid companies and government were put forward to provide reference for the grid to absorb more renewable energy generation such as wind and solar energy and to promote the improvement of power supply structure.