In　the　harmonic　power　flow　calculation　of　the　power　grid,　the　indeterminacy　of　new　energy　generation,　the　volatility　and　intermittency　of　nonlinear　load　will　lead　to　the　uncertainty　of　the　injected　harmonic　current.　In　order　to　deal　with　the　uncertainty　information　in　the　power　grid,　relative　distance　measurement　(RDM)　is　used　instead　of　point　values　to　describe　the　uncertainty　of　distributed　generations(DGs)　output　and　state　variables.　In　this　paper,　the　RDM　harmonic　source　model　is　built　to　solve　the　interval　harmonic　power　flow.　Through　a　typical　33-node　distribution　network　calculation　example,　it　is　testified　that　the　RDM　Power　flow　algorithm　has　sufficient　completeness　and　low　conservatism　compared　with　the　traditional　interval　algorithm　and　Monte　Carlo　method.　©　Published　under　licence　by　IOP　Publishing　Ltd.