Abstract: Spatial direction relation theory affects design, development and application of GIS, which is given a high recognition by International GIS and related academia, so it is important to research on the models. When the scale changes, uncertainty of special data is variable accordingly, which impacts description of spatial relations. This paper develops models to describe cardinal directions，considering uncertainty variety of spatial data because of scale change, and determine critical values between cardinal directions to remedy 9-intersection matrix. The model partitions the direction relations with smooth transition regions, which accords with percipience on direction concept description.