China is one of the counties in the world that suffers the most natural disasters. Geographic Information System (GIS) plays a significant part in different stages of disaster prevention and reduction. However, current systems existing for disaster reduction in various sectors mainly serve for single kind of disaster and usually have their own special data formats for input and analysis that result in low efficiency, digital divide and incompatible among them. Consequently, to build an integrated platform to facilitate disaster reduction and standardize disaster management in national scale is urgent and necessary. This paper describes the design and construction of such a system combing natural disaster models with capacity provided by GIS in a uniform and flexible decision support environment. Especially it presents a mean leveraging ArcGIS technology to build a software system loosely coupled between common GIS component and model bank containing expert knowledge.