A series of polynuclear gold(I) sulfido complexes of bis(diphenylphosphino)amine ligands has been synthesized and characterized. A rather small variation in the conformation of the bis(diphenylphosphino)amine ligands has led to distinct differences in the identity of the polynuclear gold(I) sulfido complexes formed. Unprecedented concentration-dependent and solvation-dependent reversible cluster-to-cluster transformation between a dodecanuclear gold(I) sulfido complex (L-Me-Au-12) and a hexanuclear gold(I) sulfido complex (L-Me-Au-6) has been observed. The transformation process has been monitored not only by H-1 and P-31{H-1} NMR spectroscopy but also by UV-vis absorption spectroscopy and high-resolution electrospray ionization mass spectrometry (HR-ESI-MS) in the solution state. This work has provided a simple approach to achieve structure modulation of gold(I) sulfido complexes and an understanding of supramolecular transformations via external stimuli.