Abstract: The stepping motion of the control rod drive mechanism is a complicated dynamic process combined with electromagnetic field, flow field, and motion. It is not accurate to analyze the process by static method or partial technique. Magnet software, Fluent software, and Adams software were combined to conduct the coupling calculation of gravity, electromagnetic force, hydraulic resistance, and spring force during the stepping motion of the control rod drive mechanism. The electromagnetic force, hydraulic resistance, displacement and velocity of movable parts, and stepping loads were calculated quantitatively. The calculated values of the movable pole closing time, critical current and stepping loads were compared with the corresponding experimental values. The calculated values were in consistence with the experimental values. It is proved that the united simulation is an effective dynamic analysis method for the stepping motion of the control rod drive mechanism.