When the traditional method lacking in adapting requirement variety, some agile software development methods appears, which flexible development mechanism could control the risk that requirement variety brings. Taking Extreme Programming as an example, this paper introduces ideas, values and process practice rules of agile methods. Extreme Programming is a software development methodology that is agile and based on practice. This paper introduces the features of Extreme Programming and how to practice Extreme Programming in developing management information system, also discuss and study the advantages and disadvantages when applying Extreme Programming in small or middle sized projects with inconstant requirements.