The stability of water supply is the key to the sustainability of the World Cultural Landscape Heritage of Honghe Hani Terraces. Taking the Quanfuzhuang River basin located within the core area of the heritage as the object, we obtained the spatial distribution and structural characteristics of rivers and ditches based on QuickBird image and field survey. We selected slope and the distance between rice terraces and rivers or ditches or river-ditches network as the two resistant factors, and analyzed the connectivity of riverditches based on the least-cost distance model in ArcGIS. The results showed that: (1) the ratio of line to node, connectivity and circuitry index of river-ditch network were bigger than those of rivers or ditches; (2) the irrigation resistance of the Hani Terraces by rivers and ditches was higher than by river-ditch network. 66.4% of the total terrace area got stable water irrigation by riverditch network. (3) Taking the self-irrigation and twoway irrigation terraces into account, the highest stable area and higher stable area of water irrigation of the Dayutang village increased by 3.9% and 5.7%, while those of the Xiaozhai village increased by 3.2% to 5.9%, respectively, which indicated the increased stability of water irrigation of Hani Terraces. (4) According to the field survey, the connectivity of river-ditches calculated through the least-cost model can be used for reasonable classification of water irrigation stability, and the results can be used for decision making of maintaining the terrace landscape.