Abstract : We have proposed the formal specification language RLOTOS ( Reflective LOTOS) which is an extension of LOTOS. It has reflective computationfacilities and layered architecture which contains object level and meta level as other reflective languages. On meta level there is an interpreter which executes the object level description, and we can change the behaviour of the object level by controlling the interpreter. In this paper, we present an environment for the formal specification development in RLOTOS. The environment provides some useful tools for representing the meta information which is the behaviour of object level.