Energy saving technology is playing an increasingly important role in green building. This paper summarizes the development of green building energy-saving technology at home and abroad. Based on the case of Suzhou Mingxin Environmental Science and Technology Building, uses digital simulation software for light insulation, insulation performance of exterior, annual load situation. The paper analyzes the application effect of energy saving technology in this case, combines the theory with case, compares the influencing factors, and puts forward suggestions to improve the indoor health environment, which is the reference for the further development of green building in China.