Elucidating　the　microstructure　of　hard　carbon　is　essential　for　uncovering　the　sodium　storage　mechanism　and　constructing　state-of-the-art　hard　carbon　anodes　for　sodium-ion　batteries.　Guided　by　an　understanding　of　the　crystallization　process　and　inverse　materials　design　principles,　we　design　hard　carbon　anodes　with　different　local　fragments　to　understand　the　correlation　between　the　microstructure　of　hard　carbon　and　sodium　storage　behavior　from　the　commercialization　perspective.　The　sodiation　transformation　of　hard　carbon　from　slope-　to　plateau-type　is　realized　via　a　series　of　local　structure　rearrangements,　including　tuning　of　the　interlayer　distance,　average　crystallite　width　of　graphitic　domains,　and　defect　density.　We　found　that　the　increase　in　plateau　capacity　is　mainly　related　to　the　transition　from　the　critical　interlayer　distance　to　the　average　crystallite　width　of　graphitic　domain　control,　and　is　limited　by　the　closed　pore　volume　of　hard　carbon.　During　sodiation,　the　formation　of　NaF　and　Na2O　in　the　slope　region,　as　well　as　Na2O2　and　NaO2　in　the　plateau　region,　is　always　accompanied　by　the　production　of　Na2CO3.　This　work　provides　insights　into　understanding　the　sodium　storage　behavior　in　hard　carbon　anodes　and　defines　general　structural　design　principles　for　transitioning　from　slope-type　to　plateau-type　hard　carbon.　©　2025　The　Royal　Society　of　Chemistry.