Abstract: Agile software process may become one of the most rational development patterns in global economic environment, as it can assist software enterprise to make rapid response to the market. Firstly agility requirements of software development are analyzed systemically, and its five characteristics are summarized, such as concurrency, light-weight process, time-based, just enough, and component based software development. Then FLEX language is provided to model agile software process from the three abstract levels. Based on process model, nine static analysis and dynamic simulation technologies are also presented to improve the agility of software process.