Currently, the power GIS system mainly adopts two-dimensional electronic map to show the power network and related information. But, it's difficult to meet the panoramic display requirement due to lack of vertical viewing angle. This paper introduces a visualization method based on Cesium and 3DCityDB to achieve panorama visualization of power data in 3D virtual environment. The map data of study area is extracted from OpenStreetMap, and used to model city buildings. Power objects and features are designed, and managed by 3DCityDB. Power web 3D GIS communicates with server side by web feature service. Finally, the 3D system is deployed, and its functions are tested. Through this study, we extend the power 3D-GIS to B/S architecture. It is beneficial for the power 3D-GIS to cross platform. The tools used in this paper are open source software and convenient for system upgrade.