Software testing，whose main task includes the selection of test cases，is verv important in software development．Since selecting test cases manually is USuallv blind and with great tendency，it is necessary to develop a tool which can generate test cases automatically．This paper first introduces some concepts and methods used in Ada software test case generation，and then puts emphasis on the application of function minimization method and instrumentation techniques，finally it describes the design and implementation of TCGT——the Ada software test case generation tool．