The procedure for expressing OWL rough ontology can be divided into seven steps: (1) define “PreciseClass” as precise class, define “RoughClass” as rough class; (2) define “Accuracy” as the approximation accuracy of the object; (3) define “SubClassOf’ as inheritance relations between rough concepts represent inclusion relations based on the intension; (4) define “Low_extent” as lower approximation extension of rough concept; (5) define “Up_extent” as upper approximate extension of rough concept; (6) define domain of definition as rough class; (7) define function range as precise class.