需求分析是信息系统或软件开发生命周期中一个重要阶段，并具有自己的生命周期。需求分析具有迭代性、演进性和并行性三大特性。通常，需求分析方式隐含在各种系统开发模型中，20世纪90年代初以来，随着需求工程热潮的掀起，需求分析模型的研究也成为研究热点。Theofanos等在总结分析已有需求分析模式的基础上，提出了需求分析浪峰模型。该模型同时反映了需求分析的三个特性，刻画了需求分析的复杂性，充分体现了需求分析的发展新趋势。该文根据GIS特点，对该模型进行了三个方面的改进：（1）将需求分析划分为5个阶段，原模型中的需求定义分解为结构化定义和形式化定义两个阶段，以便于根据该模型进一步发展GIS分析的自动化工具；（2）进一步明确了需求分析每阶段的具体分析活动以及应该采用的分析方法，使模型更具可操作性；（3）反映了项目GIS、部门GIS、企业GIS、社会GIS等不同规模和复杂程度系统开发的需求分析的差别。并对不同情况下选择需求分析模式以及结构化需求定义方法进行深入的分析，对GIS系统开发的需求分析具有现实指导意义。

Requirements analysis is an important step in an information system development cycle. It can be viewed as a process with a life-cycle of its own. The requirements analysis may includes four more basic step：domain-problem analysis， problem description，prototyping and testing，validation. It is also an iterative and evolutionary process，and a concurrent activity. Therefore，the requirements analysis model should represent the iterative，evolutionary and concurrent characteristics of requirements process activities. However，most of models resently developed only represent one or two characters of requirements process activities. The waterfront model for requirements analysis which was put forward by Theofanos can represent all characters of requirements process activities. In this paper the authors improve this model according to the characters of GIS requirements analysis activities in following aspects：① In order to develop ulteriorly the automatous tool of GIS requirements analysis in term of the model，the requirements analysis was partitioned into five basic activities：problem analysis，structural requirements description，formal requriements definition，prototyping and testing， validation. ② In order to make the model more operational，analysis methods for every activities of requirements analysis is put forward. ③ The difference of requirments analysis for project GIS，department GIS，enterprise GIS and social GIS is presented and also incorporated into the model. The methods for GIS structural requirements analysis are also discussed. This will have a guideline significance for GIS requirements analysis.