Interval　harmonic　power　flow　can　take　into　account　the　uncertainty　of　distributed　generation,　and　obtain　the　interval　results　including　all　possible　harmonic　current　solutions.　In　this　paper,　affine　arithmetic　is　used　to　reduce　the　conservatism,　which　is　a　shortcoming　of　interval　arithmetic,　and　a　Newton-Raphson　harmonic　current　iterative　equation　is　established　in　affine　form.　By　the　equal　value　at　both　ends　of　the　equation,　the　coefficients　of　noise　element　in　affine　correction　quantities　are　solved　one　by　one,　and　in　this　case,　the　complex　performance　of　Interval　affine　matrix　inversion　can　be　avoided.　The　interval　arithmetic　method　proposed　in　this　paper　is　proved　to　be　complete　enough　and　less　conservative　compared　to　the　Monte　Carlo　method　with　IEEE-30　node　example.