Reusing software is a promising solution which overcomes the software crisis in the software development environment by improving the software productivity, reliability and maintainability. To develop software, some developers reuse existing softwares, but without an adequate design environment, software reuse would not be applicable. The purpose of this paper is to design and implement the X system, and measure empirically its resuability in the development phases. The development processes of the X system used a software reuse design guidelines within the Object-Oriented Design method and the Ada programming language. In order to measure the resuability, metrics was proposed and applied for each phase of development. The results of this paper address some reusability measurement that may be used as basic data when estimating the amount of reuse for a combined development project of military applications.