Poly-NHC-based organometallic assemblies 3-PF6, 3-SbF6 and 3-OTf were obtained and verified by NMR spectroscopy, ESI mass spec-trometry and single-crystal X-ray diffraction analyses. Controllable structural interconversion was observed between the poly-NHC-based organometallic assemblies and their self-aggregated dimers in solution affected by concentration, solvent and metal ion. 1H NMR spectra of assembly 3-PF6 in CD3CN at different concentrations demonstrated controllable structural interconversion, and 19F NMR spectrum of assembly 3-PF6 at high concentration further evidenced the presence of the free hexafluorophosphate anion and en-capsulated hexafluorophosphate anion for its two sets of signals. In addition, single-crystal X-ray diffraction analysis provided clear evi-dence that in the solid state, two assemblies 3-PF6 were vertically stuck, forming a self-aggregated dimer with an encapsulated hex-afluorophosphate anion. Investigating the reversible structural interconversion is beneficial for revealing the intrinsic nature on the atom level and paving the way to design the stimuli-responsive functional system.