Pyrite　autotrophic　denitrification　(PAD)　is　a　cost-effective　and　promising　method　for　nitrogen　removal　from　low　C/N　wastewater.　Recent　work　has　primarily　focused　on　experimental　schemes　to　investigate　PAD　performance,　while　overlooking　the　impact　of　pyrite＇s　origin　on　its　mineral　properties　and　chemical　reactivity.　Thus,　the　optimal　strategy　for　selecting　pyrite　based　on　the　structure-activity　relationship　between　its　mineral　characteristics　and　PAD　performance　remains　unclear.　In　this　work,　a　series　of　PAD　systems　were　established　using　natural　pyrite　from　different　origins　as　electron　donors.　The　results　showed　that　the　pyrite　from　Yunfu　(B-YPy38　and　B-YPy48)　exhibited　the　optimal　performance,　with　nitrate　(NO3−-N)　removal　rates　of　88.56　±　0.60%　and　72.26　±　3.10%　after　long-term　operation,　respectively.　The　distinct　nutrient　removal　efficiency　could　be　attributed　to　variations　in　the　mineral　crystallization　habits　and　electrochemical　properties　of　pyrites　from　different　origins.　XPS　analysis　revealed　that　the　pyrite　from　Yunfu　contained　more　Fe(III)-S　bonds　associated　with　the　breakage　of　pyrite　crystal　structure,　thereby　accelerating　the　＇oxidation-dissolution＇　process　of　pyrite　to　produce　Fe(II)　and　S0,　thus　providing　more　electron　donors　for　autotrophic　denitrifying　bacteria　(e.g.,　Rhodanobacter　and　Thermomonas).　Electrochemical　analysis　further　indicated　that　the　stronger　Fe(II)/Fe(III)　cycling　capacity　in　pyrite　from　Yunfu　might　enhance　electron　shuttling　between　pyrite　and　NO3−-N.　Microbial　community　analysis　revealed　that　the　higher　chemical　reactivity　and　electron　transfer　in　YPy38　and　YPy48　promote　the　enrichment　of　autotrophic　denitrifying　bacteria.　These　findings　shed　new　light　on　understanding　microbial　processes　in　PAD　systems,　offering　a　theoretical　basis　for　the　optimal　selection　of　pyrite　to　enhance　PAD　efficiency　for　further　application.　©　2025　Elsevier　B.V.