Rapid prototyping as a new method for software development is actracting great attention．The XYZ system is a CASE environment based on temporal logic and con forming to various ways of programming．The method for software development supported by the XYZ system is that of“formally specifying the target system，and then verifying or rapid prototyping the specification in a way of stepwise refinement till the effectiveiy exe cutable programs are obtained”．This method not only can make every steps in the evolu-tion procedures froom abstract specification to effectiveiy executable programs natural and eiear，but also can evaluate the correctness of the results of refinement in order to discover the problems and resolve them eariler．In this paper，the authors present and discuss the rapid prototyping which will be applled to the software development with the support of the XYZ system and the software tools——XYZ/PROT with which they support the rapid prototyping by construction the PROLOG prototypes from the specifications in temporal logic and executing the prototypes．