The steam generator is very important for the safe operation of the whole nuclear power plant. During the long operation of the steam generator, the foreign objects carried by the secondary fluid will cause the vibration, wear, fatigue and even rupture of the heat transfer tube, which will affect the safety and reliability of the steam generator. In order to avoid serious damage to the steam generator by foreign matter, it is necessary to evaluate the impact of foreign objects on the steam generator tube and take appropriate measures according to the evaluation of results. In this study, CFD coupled with Discrete-Element Method was used to build a numerical simulation method for the calculation of foreign objects movement on the secondary side of steam generator to carry out numerical simulation of foreign objects movement trajectory, describe the dynamic characteristics of foreign objects, and obtain the law of foreign objects movement on the secondary side of steam generator.