Abstract: This paper presents three model expressions，classified as the Graphic Meta Expression （GME），the Regular Expression （RE） and the Model Computing Tree（MCT），which are aimed to express model content in the Model Base System.These expressions are very useful in describing the content of the model，when they are compiled to the model component by the Just Intime compiler Technology（JIT）.The method perfectly resolves the problem of expressing a model content，including the procedure，formulation and parameter.In the end，the demonstration shows the optimization and flexibility in applying these expressions to build a model executing body.

Key words: Model Base System（MBS）, Graphic Meta Expression（GME）, Regular Expression（RE）, Model Computing Tree（MCT）

摘要： 提出模型库系统中模型的三种表达方式——图形图元表达、正则表达式及模型运算树。它们可作为动态生成高效率模型体的有力手段，是模型库系统即时编译生成模型组件的基础。这为解决模型库系统实现过程中模型内容表达这一难题，提供理论基础及解答。最后，在此概念及原理基础上，给出了采用这三种表达方式展现原型系统中范例模型的具体过程。

关键词: 模型库系统, 图形图元表达, 正则表达式, 模型运算树