Choosing of adequate shape technological parameters together with good chemical compound is very important to produce steel strip with required cross-section and material quality. The shaping rate, speed and time have an effect on strip mechanical and geometrical quality. The rate of shaping force needed for steel strip plastic deformation is determined by the strength of the steel forming. In rolling mills technology the plastic deformation of the strip is realized at high plastic strain speed so the dynamic change of shaping force might seriously affects the remaining stress of the rolled strip. The dynamic control of roll gap and force is realized with help of electrohydraulic servo actuator – so-called hydraulic capsules – which can adjust the roll gap at great rolling force dynamically. The quality of stand-mounted hydraulic capsule can greatly affect the dynamics of rolling, consequently the material quality of the rolling. The main contribution of the paper is to analyze the rolling dynamic behavior using the hydraulic capsule and rolling mill mathematical model together to show the changing of dynamic behavior of the system when internal sealing in hydraulic capsule is inefficient.