Formal specification as a precise description of software requirements plays an important role in the software development processes. It can be used as a measurement for validating the artifacts of almost all stages in the development process. Hence, making effort on validating the correctness of the formal specification against the requirements in the very early stages of development is of a high value. Extracting prototype from formal specification can be a kind of such a validation. In this article, we propose a translation set of rules for building executable prototypes written in SetL2 language from formal specification in Z formal language. Then, we investigate the correctness of the translation with help of some lemmas based on weakest precondition predicate transformer and refinement relationship.