Abstract: Formal specification of diagrammatic languages is not applicable to end users because of the requisition of computer theory. In order to satisfy the requirement of end users to define their own domain-specific modeling language, a language named EUVDL(end-user visual definition language),was proposed, which could be used to specify the 2-dimensional syntactic structure of diagrammatic model in software engineering. The specification technique of EUVDL combined the object-oriented methods and the rule-based approaches rather than formal specification. The support to end users was provided from following aspects: paradigm, abstract syntax, and concrete syntax. In order to make EUVDL available, the practical strategies for end users were presented and a framework for diagrammatic modeling environment generator was designed. Through comparison to other specification methods and demonstration of an example of visual process model, the conclusion can be drawn out that the specification method has the feature of simple structure, expressive power and reusable ability, and is adapted to end-users.