Region is one basic unit of spatial analysis in GIS applications

which is a kind of entity existing widely in many fields such as environment science

land information science and so on. In general

the kind of entity has a common character of continuously spatial distribution

so there is inevitably fuzziness in spatial data used to represent its position when it is abstracted and generalized

and enters into GIS databases. Here

fuzzy set is taken in this paper as a strong and convenient mathematical bridge to model uncertainty and fuzziness under a GIS environment. Firstly

a new method of representing fuzzy region is proposed based on field model

and its spatial uncertainty is analyzed. On the basis of above discussion

we analyze some existing methods on how to describe the point set topology of fuzzy region by referring to some shortcomings and giving a kind of new description method. Thus fuzzy region’s boundary

interior and exterior are defined in detail

and their geometric meanings are given. Finally

this paper ends with the discussion on how to describe uncertain topological relations caused by spatial uncertainty of fuzzy region based on the point set topology

and develops corresponding 9

i

ntersection models. It is shown that the point set topology model proposed in the paper is an extension of the 9

i

ntersection model by Egenhofer （1991）.