Modulating　the　electron　delocalization　of　catalysts　can　improve　the　activation　and　conversion　capabilities　of　lithium　polysulfides　(LiPSs)　in　lithium-sulfur　batteries,　while　the　precise　mechanism　underlying　this　enhancement　remains　unclear.　Herein,　a　p-block　In　single-atom　catalysts　(In-N4)　is　constructed　with　moderate　electron　delocalization　via　axial　coordination　engineering　of　gallium　nitride　(GaN),　which　exhibits　the　best　adsorption　and　electrocatalytic　activity　toward　LiPSs.　In　situ　characterization　analysis　combined　with　advanced　theoretical　calculations　demonstrate　that　the　axial　In-N-Ga　coordination　induces　the　electron　transfer　from　In　sites　toward　the　N　sites　of　GaN　and　the　unconventional　sp3d2　hybridization　interactions　of　In　sites.　This　further　helps　to　optimize　adsorption　configuration　through　the　orbital　hybridization　between　sp3d2　hybrid　orbital　of　In　sites　and　p　orbital　of　S　atoms　in　LiPSs,　namely　the　sp3d2　-　p　orbital　hybridization,　which　can　weaken　S-S　covalent　bonds　of　LiPSs　and　significantly　accelerate　the　sulfur　reduction　reaction.　Accordingly,　the　capacity　decay　of　lithium-sulfur　battery　with　In-SA/GaN　catalyst　is　only　0.040%　per　cycle　over　800　cycles　at　5　C.　The　stacked　pouch　cell　delivers　a　reversible　capacity　of　600　mAh　after　100　cycles.　This　work　elaborates　on　the　activity　origin　of　p-block　metal　catalysts　and　provides　a　new　perspective　on　designing　advanced　catalysts　for　other　catalytic　systems.