To reduce building lighting energy consumption and carbon emissions,light tube daylighting systems have gradually been applied in architecture. With their features of safety,energy efficiency,health,environmental friendliness,and compliance with the new green building rating standards,light tubes have gained recognition from architects and building owners. This paper introduces the specific engineering application of light tube daylighting in the newly built library hall of our school. It also presents the actual illuminance measurements taken from the floor of the hall,with results showing that the illuminance meets the national standards requirements. Additionally,the article analyzes and calculates the energy-saving data and the carbon emissions reduction achieved by using light tube daylighting.