Water hammer is common in nuclear facility pipeline systems, such as nuclear chemical system and essential service water system (SEC). Water hammer can cause a large fluctuation of fluid pressure, posing a threat to the normal operation of devices and instruments, accompanied by pipeline systems vibration and noise. The inertial component can be used to simulate two types of components in the nuclear facility pipeline system. One is the short joint pipe between the main pipe and the pressure regulator, and the second is the neck, short joint pipe or water storage pipe inside the equipment. Therefore, it is necessary to study the influence of inertial component in the water hammer process. The water hammer theoretical model was established, and the unsteady friction was considered. The water hammer performance experiment rig was conducted, and the experiments were carried out. The model results agreed well with the experimental data. The inertial component was added to the pipeline system, and its influence was studied by two analysis methods. The analysis results show that as the inertial component moves from downstream to upstream, the initial fluctuation amplitude of pressure and kinetic energy decrease, the internal energy and total energy increase, the fluctuation period increases, and the friction loss word decreases. As the inertial component coefficient increase, the fluctuation amplitude of pressure, kinetic energy, internal energy and total energy increase, the fluctuation period increases, and the friction loss word increases. And the kinetic energy and internal energy are periodically transformed in the water hammer process. The research results provide guidance for the inertial component analysis in the nuclear facility pipeline system.