This paper presents a fluid-dynamic analysis of the hydraulic circuit of a shaking table for seismic tests; the model was developed adopting a commercial code. The aim of the study is to provide useful indications for the design of a new optimized control system. The model was developed taking into account all the components of the hydraulic circuit that is made of by the following main items: the axial piston pump, the pressure relief valve, the main control valve, the accumulators, the hydraulic cylinder with variable displacement and all the connecting pipes. Particular attention was given to the modelling of internal resistance of the hydraulic system, that can greatly affect the performance of the shaking table. It has also been accurately modelled the main valve dead zone to highlight its influence on the system dynamics. The results of numerical simulations obtained for different operational conditions are reported and compared with experimental data to show the validation and the performances of the developed model.