The current investigations of building seismic damage are mainly dependent on manual work, leading to a low efficiency. To improve the efficiency of the investigation, a system for the investigation of building seismic damage based on smartphones and Web technique is developed. This system is made of three components: a server, smartphones and a web. In the server, a building-oriented database is built, which makes buildings become the basic elements for the data collection and management. In smartphones, an app for collecting data is developed, which builds a corresponding relationship between the collected multi-media data and buildings. In the web, the data collected by smartphones are analyzed and stored. In addition, these data are visualized on a GIS cloud platform. The system has been successfully applied in the investigation of building seismic damage in Tibet area in the 2015 Nepal earthquake.