In actual construction engineering, the emergency lighting power supply should be selected according to the structure of the layer number, size, complexity, how many buildings stay and mobile people, the production and use of building characteristics, fire danger degree and the importance of the buildings, and other emergency power Settings And so on, comprehensive consideration for technical and economic analysis and comparison, choose the optimal emergency lighting power supply. The combination power supply mode has the advantages of more than two kinds of power supply, and the unilateral disadvantages can complement each other. Although the investment is large, it is still widely used in high-rise buildings and some particularly important large buildings due to its high reliability.