In　this　study,　humic　acid　(HA)　enhanced　17　beta-estradiol　(17　beta-E2)　degradation　by　Er3+-CdS/MoS2　(ECMS)　was　investigated　under　ultrasonic　and　light　conditions.　The　degradation　reaction　rate　of　17　beta-E2　was　increased　from　(14.414　+/-　0.315)　x　10(-3)　min(-1)　to　(122.677　+/-　1.729)　x　10(-3)　min(-1)　within　90　min　sonophotocatalytic　(SPC)　reaction　with　the　addition　of　HA.　The　results　of　quenching　coupled　with　chemical　probe　experiments　indicated　that　more　reactive　intermediates　(RIs)　including　reactive　oxygen　species　(ROSs)　and　triplet-excited　states　were　generated　in　the　HA-enhanced　sonophotocatalytic　system.　The　triplet-excited　states　of　humic　acid　((3)HA*),　hydroxyl　radical　(center　dot　OH),　and　superoxide　radical　(center　dot　O-2(-))　were　the　dominant　RIs　for　17　beta-E2　elimination.　In　addition,　the　energy-　and　electron-transfer　process　via　coexisting　HA　also　account　for　12.86%　and　29.24%　contributions,　respectively.　The　quantum　yields　of　RIs　in　the　SPC-ECMS-HA　system　followed　the　order　of　(3)HA*　＞　H2O2　＞　O-1(2)　＞　center　dot　O-2(-)　＞　center　dot　OH.　Moreover,　the　spectral　and　fluorescence　characteristics　of　HA　were　further　analyzed　during　the　sonophotocatalytic　reaction　process.　The　study　expanded　new　insights　into　the　comprehension　of　the　effects　of　omnipresent　coexisting　HA　and　RIs　formation　for　the　removal　of　17　beta-E2　during　the　sonophotocatalytic　process.