To provide a heat exchange equipment diagnostic system for grasping relationship between a flow rate of fluid and a heat transfer coefficient or a change in the heat transfer coefficient and diagnosing deterioration in heat exchange equipment.

In the heat exchange equipment diagnostic system for grasping an operation state of the heat exchange equipment by simulation, a heat transfer coefficient is selected by using a tracking simulator for reproducing a state of a real plant in real time based on a measurement value of the real plant as a tracking parameter, the tracking simulator is driven in parallel with the real plant, estimation values of the heat transfer coefficient are found out by adjusting the heat transfer coefficient until the measurement value matches a simulation value, and a deterioration state of a heat transfer performance in the heat exchange equipment is determined based on a change tendency of these estimation values.