In　this　paper,　a　special　class　of　neighborhood　systems,　called　reflexive　1-neighborhood　systems　is　introduced,　properties　of　neighborhood　and　approximation　operators　are　studied,　and　their　connections　are　examined.　In　addition,　this　paper　discussed　incomplete　systems　from　view　of　point　of　information　view,　and　in　order　to　measure　uncertainty　of　knowledge　and　roughness　of　rough　set　in　incomplete　information　systems　knowledge,　the　indiscernibility　relation　in　classical　rough　set　theory　is　necessary　to　be　extended　to　some　more　general　relations.　Furthermore,　information　entropy　is　introduced　to　study　the　rough　entropy　of　knowledge　and　the　roughness　of　the　rough　set　based　on　covering　granules,　which　are　described　with　reflexive　1-neighborhood　systems.　Finally,　a　new　kind　of　measurement　about　the　roughness　of　knowledge　and　rough　set　is　proposed.