Ligand　functionalization　has　been　considered　as　an　efficient　strategy　to　modulate　the　properties　of　metal-organic　frameworks　(MOFs).　In　this　work,　a　series　of　functionalized　UiO-66(Ce)-X　(X　=　H,　CH3,　Br,　NO2)　have　been　successfully　synthesized　for　the　photocatalytic　oxidation　of　benzylamine　under　visible　light.　The　UiO-66(Ce)-CH3　exhibited　the　highest　conversion　among　the　samples.　The　quantity　and　the　acid　strength　of　coordinatively　unsaturated　Ce　sites　as　Lewis　acid　sites　are　modulated　by　ligand　functionalization,　both　following　the　order　of　UiO-66(Ce)-CH3　＞　UiO-66(Ce)-H　＞　UiO-66(Ce)-Br　＞　UiO-66(Ce)-NO2,　which　is　closely　related　to　photocatalytic　performance.　Based　on　in　situ　FTIR　results,　coordinatively　unsaturated　Ce　sites　can　facilitate　the　activation　of　benzylamine　molecules　via　the　surface　-CeN-　coordination　species,　and　the　activated　degree　of　the　N-H　bonds　is　evaluated　and　compared　via　the　force　constant.　In　the　photocatalytic　process,　photogenerated　holes　achieve　the　deprotonation　of　activated　benzylamine　molecules　to　form　benzylamine　cations,　and　photogenerated　electrons　captured　by　oxygen　vacancies　simultaneously　reduce　activated　O2　to　form　O2−,　effectively　achieving　this　selective　photooxidation.　Finally,　a　synergetic　photocatalytic　mechanism　associated　with　the　coordination　activation　was　proposed　to　explain　this　reaction　process.　©　2022　The　Royal　Society　of　Chemistry.