Abstract: It is an important approach to reconstruct the energy-saving heating system of an existing residential building in reducing its energy consumption.The technology of energy-saving reconstruction consists of two aspects,one is architectural energy-saving,and the other is heating energy-saving.Energy-saving reconstruction mainly takes the energy-saving reconstruction of envelope structure and renewable energy sources into consideration.It plays a key role in analyzing the comprehensive efficiency and reasonable technology in the process of reconstruction.It is analyzed the technology of energy-saving reconstruction of wall for envelope structure,and put forward some measures in energy-saving reconstruction of existing residential buildings.