This paper describes the results of a study focused on the mathematical modeling of an excavator hydraulic system. From the viewpoint of designing and tuning an efficient control system, the excavator is a very complex nonlinear plant. To design and tune such a complex control system an extremely good nonlinear model of the plant is necessary. The problem of modeling an excavator is considered in this paper; a nonlinear mathematical model of an excavator has been developed using the AMESim® modeling environment to replicate actual operating conditions. The excavator model is described by detailed models of the main pump, valve block and kinematic model. The objective of this research is to develop a complete simulation model of an excavator with the capability of reproducing the actual characteristics of the system. The model could then be used as a platform to facilitate the study of alternate control strategies towards energy efficient systems and new controller designs for HIL. The novelty in the modeling approach is that the detailed component models have been developed to replicate actual conditions while not being demanding on computational time. This has been achieved through a balance of semi-empirical models, while maintaining the flexibility of varying the gain characteristics of the components for enhancing system performance. The benefit of this model is it provides an advantage on computational time for complex system modeling while not compromising on the systems characteristics. Hence, this paper presents the developed model of a complete excavator system with detailed verification of individual components and preliminary results of a complete excavator system.