Abstract: In order to resolve the disadvantage that similarity models of space direction relations do not consider the uncertainty of space target, by means of the advantage that rough-set expresses uncertainty problems, rough-set expression method of space direction relations is defined in cone-shaped models of cardinal direction relations.The computation and rough-set expression method of similarity of multi-scale space direction relations based on the positional uncertainty of space target are proposed, this method makes that the value of similarity of multi-scale space direction relations is varied in a interval, which accorded with human cognition of similarity of multi-scale space direction relations