Air conditionings take major energy consumption in intelligent buildings. And now, with deep research and widely application of building automation technology and air conditioning control technology, indoor air conditioning is going from a single refrigeration system to a multifunctional system such as changes in temperature, low noise, energy saving and environmental protection. Lon Works is a famous kind of fieldbus because of its open and interoperability. Its characteristics of neuron chip makes developing LonWorks devices much easy. In this paper, monitoring system of heating ventilation air conditioning (HVAC) based on LonWorks and KingView is studied. At first, a LonWorks control network for HVAC is built up. The iLON6OO Lon Works/IP server is used to connect LonWorks devices with PC. Secondly, LonWorks node is designed. Three modes are adopted for HVAC. Afterward, monitoring software based on KingView is completed on PC. The experimental results validate the feasibility of the proposed control system and its application of actual engineering. (5 pages)