Building energy consumption is an important component of the total social energy consumption, especially for large public buildings in China. Building energy conservation is one valid method for increasing energy efficiency. In order to locate the status of energy consumption for large public buildings, such as supermarket, government office buildings, hospital and campus buildings, an Internet-based energy monitoring system was developed. The implementation of this system was introduced in detail, including the principle of selecting monitoring points at the bottom layer, the design of a data collector with storage function avoiding data loss caused by network faults, and the development of database and application software at the top layer. The monitoring platform releases the energy consumption data on the web, so the authorized users can access the data any time and anywhere through Internet. In addition, the data display system is given in form of graph-charts or tables, so users can choose any kind of data they want to see, either instant values uploaded every 5 min or historic data uploaded every hour, day and month. The platform has been used in some large public buildings in Liaoning Province in China over two years, and the results confirm its feasibility and validity.