A　rare　cadmium-containing　windmill-like　heteropolyoxoniobate　macrocycle　has　been　successfully　synthesized　with　stable　1-D　cyclic　cluster　aggregates.　The　compound　exhibited　promising　basic　catalytic　ability　for　Knoevenagel　condensation　with　a　high　yield　under　mild　reaction　conditions　and　high　cycling　stability.　The　theoretical　calculation　showed　that　the　promising　basic　catalytic　ability　is　due　to　the　dense　and　stronger　basic　sites　of　the　surface　terminal　O　atoms.　©　2023　The　Royal　Society　of　Chemistry.