Abstract: Thermal power plant is the key node of energy conversion, and the operation efficiency of transmission and distribution system directly affects the energy consumption level and carbon emission intensity of the whole network. At present, there are some problems in energy-saving self-optimizing control, such as lagging voltage regulation and large deviation of line loss estimation, which makes it difficult to realize refined energy-saving regulation. Therefore, this paper proposes an energy-saving self-optimizing control method for power transmission and distribution lines in thermal power plants. Calculate the voltage point of the minimum current, and carry out intelligent voltage regulation of power transmission and distribution lines in thermal power plants; by reducing the thermal loss, the resistance in transmission and distribution lines is calculated to control the line loss; according to different load states, the optimal working voltage is selected to realize the single variable energy-saving self-optimization control of transmission and distribution lines. The experimental results show that the voltage of power transmission and distribution lines fluctuates within its safety threshold after controlling the energy-saving self-optimization of power transmission and distribution lines, and the line loss is effectively reduced.