Information about the dynamic loading of a steel structure is important for its static design as well as for an assessment of its fatigue life. In the case of a hydraulic static-pile-pressing machine, these loads are mainly caused by vibrations and load sway, which occurs as a result of the slewing motion of the boom around the vertical axis and from the radial movement of the load’s suspension point. This paper presents the study of the dynamics of a hydraulic static-pile-pressing machine during the process of lifting and slewing a pile using a mounted crane. A six-degree-of-freedom non-linear spatial-dynamic model is employed and a non-linear mathematical model of the machine is formulated. To confirm the mathematical model, the comparison between the measured results and simulation results using the mathematical model shows that the mathematical model is reliable. These results can be used to optimize the machine design based on calculations of its dynamics, fatigue, life expectancy and stability from a dynamic point of view.