Actual problems during design, implementation and maintenance of securities settlement systems software are achieving complementarity of several different, connected, asynchronously communicating settlement systems and verification of this complementarity. The aim of this paper is to create domain specific language for modeling of settlement systems and their interactions. Then use models to calculate settlement systems behavior. Specific of settlement systems requires that they perform accordingly to business rules in any situation. This makes use of model checking a very desirable step in development process of settlement systems. Defining a domain specific language and creating editor supporting it is a first step to enable use of model checking techniques. Created models also can be used as input for other analysis methods and tools, for example, basis path testing, simulation and as base for deriving test cases.