XYZ system consists of a temporal logic language XYZ/E and a group of CASE tools based on it. The language XYZ/E is designed to facilitate the software engineering methodologies such as stepwise refinement, specification and verification, rapid-prototyping, and in particular, to be able to represent the dynamic aspects of the real time communicating process. With a uniform framework, it can represent not only the specifications of different abstract levels but also almost every kind of significant features in conventional imperative languages. This paper is the most updated and detailed introduction of this temporal logic language in Chinese.