Considering the status quo of formal language researches both at home and abroad,this paper preliminarily investigates the mathematic model of formalization specification description language for formal system and establishes an algebraic model of formal language. Moreover,the concept of language reuse is presented based on the software reuse and transformational semantics methods,and a formal language family model is set up according to the hierarchical design principle of software engineering. In this model,the degree of the abstract expression of software specification
for the complex formal system is described at different levels,which is suitable for the deve-lopment and testing of complex formal systems. Besides,the inherent relationship among the language models in the language family model is deeply analyzed based on the category theory,so as to provide a convenient and efficient theoretical framework for formal language models.