With the development and progress of the construction industry,the number of existing buildings is constantly increasing,and the renovation of existing buildings is gradually becoming an important form of urban construction and renewal.This paper introduces the design process of the existing buildings,distinguishes the electrical design contents according to the different scope and functions of the transformation,and focuses on the problems and optimization measures of the existing buildings at the present stage.Combined with the engineering examples,the main points in the existing building renovation design are fully paid attention to the key points of the new standards in the transformation from the original data collection and application to the analysis and comparison of the advantages of different power distribution system according to the current civil construction conditions.