Abstract: Object-Oriented Analysis (OOA) is introduced and a representation method of OOA is provided in this paper. Hydraulic system is selected as engineering application background. How to apply OOA method to engineering applications is discussed. According to Class-Object level, Structure level, Subject level, Attribute level, Service level these five levels, we analysis the class hierarchy of hydraulic system , their interrelation and their communication.
Keywords: Object: Object-Oriented Analysis (OOA); hydraulic system