Information techniques have been changing in the past few years. Facing the highly changeable environment, software development encounters more and more difficulties and challenges because extracting the requirements of products is getting more difficult than before. Since the correctness of product requirements is the key point determining the success or failure of project developments. However, there is no perfect solution currently. Additionally, requirements are often written in a natural language that is inherently ambiguous. One way to avoid the ambiguity is to write the requirement specifically within a particular required specification language . Consequently, requirement specification should use a special descriptive language to comprise several essential parts, namely, the purposes of specification, terms definition, specific constrains, audiences, and communication interfaces, which dominate the development effort. However, these parts have always been ignored in previous studies. In this article, we propose a requirement specification formal model which synthesizes a behavior model from the scenario  and operational software model  from goal-oriented requirement elaboration  to refer to the IEEE recommended practice for software requirements specifications . The proposed formal model may help developers produce data in proper sequence, establish the basis functional requirement according to the top level goal under inviolate limitation, specify components interaction time slide consider system essential components, and organize the outside communication interfaces of the system referring components interaction scenario.