This paper focuses on the problem of power losses in the transmission, transformation, distribution and marketing segments of the power system, and explores how to effectively improve the energy efficiency of the power grid to optimize the cost management of the power grid. The article uses principal component analysis to accurately diagnose the energy efficiency status of the grid, and analyzes the multiple factors affecting grid losses and their degree of influence. It is found that the total loss in 10km transmission line when wind power access reaches 328kw, and the complete loss of wind power access is higher than photovoltaic access under the condition of different line lengths, which are 315kw, 321kw, and 328kw, respectively. In the use of iron transmission line, the average loss at the current of 400A is 89.600W, which is higher than using aluminum alloy material by 66.200 W. If energy-efficient aluminum alloy fittings are fully utilized in transmission lines, the average annual power saving can be up to 301,368 kWh. The study shows that it is crucial to analyze the factors affecting the energy efficiency of power grids during the planning and construction stage of the power grids.