This article introduce an example of water hammer calculation using AFT software for circulating water system in a power plant. The main calculation content is to solve the fluid continuity equation and motion equation through the method of numerical simulation under given initial condition and boundary condition. As a result

hydraulic elements of each specific section of piping system at different moment

parameters such as flow

maximum reversal speed of the pump and motor and water hammer pressure under various hydraulic transient process caused by the shut down of the pump and opening/closing of the valve

etc. could be obtained. Through AFT software to optimize the circulation water system

the damage of water hammer is within controllable range

and meet the requirements of the engineering design of circulating water system of thermal power plant.