Currently,thermal power units need to undergo deep peak regulation transformation to improve the power grid's ability of large scale new energy consumption. In this paper,the deep peak regulation optimal scheduling of thermal power units under large-scale new energy grid connection is studied. Firstly,the cost of deep peak regulation of thermal units is studied and the different cost mathematical models of deep peak regulation are proposed including energy consumption,operating compensation and spinning reserve capacity. Then,taking the lowest comprehensive operating cost as the objective function,a deep peak regulation scheduling model considering the operating constraints of thermal power units is established,and the branch and bound method is used to solve the scheduling model. Finally,the test system is composed of eight thermal power units,one wind farm and one photovoltaic power station. The deep peak regulation optimal dispatching of thermal power units under large scale new energy grid connection is analyzed from the aspects of peak regulation depth,new energy consumption and thermal power enterprise income. The analysis results show that the new energy consumption of thermal power units can be significantly increased by peak regulation of thermal power units,but the benefit of thermal power units decreases significantly with the further increase of peak regulation depth. Under the current compensation standard of deep peak regulation,the benefit of deep peak regulation of thermal power units is lower than that of basic peak regulation.