Abstract: Reasoning about the inverse of cardinal direction relation is a fundamental problem in qualitative spatial reasoning and plays an important role in reasoning with cardinal direction relation and consistency checking. In order to fullfill reasoning about the inverse of the basic cardinal direction relations between regions themselves defined in the model of Goyal, after deeply researching on reasoning about the inverse of cardinal direction relation in MBR model, we propose the concept of original relation of rectangular cardinal direction relation, propose an algorithm to computer it and then develop an algorithm to reason about the inverse of basic cardinal direction relation between regions defined in the model of Goyal. The results of both analyzing in theory and verifying through comparing the result of the algorithm with the actual situation for each of basic cardinal direction relations demonstrate that the algorithm is correct and complete.