How to reduce the energy consumption of the central air-conditioning is important for the building energy efficiency. The energy efficiency reconstruction of the central air-conditioning system on one library in Guangzhou is completed with the network control system self-developed. The operational control and operational management is integrated in the network control system. The energy consumption before and after reconstruction about the air-conditioning system of the library is detected and analyzed in the paper. The result shows the mode that operational control and operational management integrated has better energy efficiency.