Abstract: In order to better understand the energy consumption of large library buildings after energy-saving renovation and evaluate the energy-saving effect after energy-saving renovation, this article conducts an in-depth analysis of the energy savings achieved after the renovation of a large library in Guangzhou. By collecting and analyzing the data of water consumption, electricity consumption and cooling capacity of the building one year before the renovation and three years after the renovation, the energy consumption before the renovation is taken as the benchmark energy consumption of the building, and the energy consumption after the renovation is taken as the energy consumption of the building during the approval period. Through the comparison of energy consumption before and after the renovation, the electricity saving rate of the building is 7.29%～23.95%, and the water saving rate is 11.94%～21.32%. The cooling saving rate is 18.69%～29.19%, and the comprehensive energy saving rate is 10.93%～25.55%. The energy saving effect of the renovated library has reached the expected effect, which provides a reference for the energy saving analysis of the same type of buildings.