This paper is concerned with a simulation study for dynamic behaviours of hydraulic shovels. The main purpose is to construct a CAE system which can design the hydraulic shovels on the display of computer with improved leveling control performance and operating feeling. Firstly, a numerical method to compute the dynamic behaviours of hydraulic shovels is presented by combining the dynamics of attachment and the characteristics of hydraulic circuit, assuming that the operator manipulation is modelled by the software of computer. Secondly, the execution time of leveling control on the display is adjusted to that of real shovels, by simplifying the modelling of the hydraulic circuit. Finally, the leveling control performance by operator manipulation is exactly evaluated by giving the parameter values of the hydraulic shovels.