地理信息共享不仅要实现数据的共享，更高一层，还应实现语义共享，GIS语义互操作，即应用层互操作是实现地理信息语义共享的有效途径。为此提出了一种新的GIS语义互操作方法--元数据调解器，它具有智能化地进行语义不一致的识别、处理，并能实现语义信息的挖掘等功能。同时给出了基于元数据调解器的GIS语义互操作体系结构，阐述了其主要思想和核心组成部分。基于这一思想，设计实现了元数据调解器的原型系统。

In order to realize Geo-information sharing, the first step is to share data, moreover, semantic sharing is its second and higher object. Semantic interoperability in geographic information system, which is the same as application level interoperability, is one of the available approaches to realize Geo-information semantic sharing. In this paper, status quo of interoperability and semantic interoperability in geographic information system are firstly probed into, and some existing methods to realize semantic interoperability are reviewed. Then, the new road—metadata mediator has been presented. The metadata mediator consists of semantic knowledge and rule bases, a semantic conflict finder and a coordinator. The mediator is implemented in the three-tier client/server architecture. Here, formalizing the metadata of geographic data and semantic expression of geographic information based on the formalizing method are two key tasks. By this mediator, semantic conflict can be recognized and processed, and semantic information mining also can be implemented. Furthermore, A prototype of metadata semantic interoperability, which is built according to the metadata mediator theory, is discussed, so far the prototype has shown its power in the National Resources, Environment &District Economy Information System (NREDIS).