Automatic optimization and degradation detection tool for HVAC primary system was developed. It synchronizes with Building Energy Management System (BEMS), and it does optimization and degradation diagnosis automatically. Generally, the tools based on the simulation are low generality because of the complex input. Therefore, the targeted system of this tool is limited to the primary system that is specific standard configuration to reduce the input data. The optimization function outputs the best set point according to the outside temperature and the load etc. The degradation diagnosis function analyzes degradation of the primary system equipment once a day. The function and the measurement result of the tool are reported in this paper.