This paper focuses on two problems occurring in modeling a hydraulic excavator. The first problem arises in the modeling process. Because a hydraulic excavator has a very complex structure, the modeling process requires considerable time and is prone to errors. This problem is solved by conceptually modeling an excavator system using bond graph methods, the top-down and bottom-up methods, and the modeling software developed by the authors, and then, automatically deriving the nonlinear symbolic mathematical model from the conceptual model by using the modeling software. The other problem arises in obtaining parameters of the model. It is difficult to obtain the specification data for hydraulic components provided by manufacturers in general and to obtain the experimental data for estimating unique parameters. To solve this problem, an estimation method is devised for estimating parameters based on the experimental data that can be easily obtained. These methods enable easy and efficient modeling of an excavator system. In addition, the established model is verified through the comparison between the simulation and the experimental results. Also, this paper provides a good example of modeling of the large complex system.