A traditional functional model is not a better representation for parallel test system because of its low level of abstraction. By raising the level of abstraction from the function - level to the object - level, object-oriented approaches can provide a better model of parallel test system. The Unified Modeling Language, or UML, is a third - generation object - oriented modeling language. And Rational Unified Process ( RUP ), which is developed and maintained by Rational Software Corporation, is based on UML, and can form a modeling approach together with UML. In this paper, object - oriented model of parallel test system will be built according to Rational Unified Process (RUP). Accompanied by RUP, a series of analysis and design documents in modeling standardization, which describe parallel test system in UML, will be formed. These documents make a contribution to the engineering realization of parallel test system.