In the current work, we designed an extraordinary supramolecular rotator composed of C 18 ring and OPP nanohoop by theoretical exploration. Precise quantum chemical calculations reveal that the perfect size matching and shape complementarity of C 18 and OPP enable them to form up to 1:2 host-guest complexes, which exist stably at temperature below 404 K. The vibrational and photophysical properties of supramolecular complexes are given to facilitate experimental identification. Various wave function analysis methods show that the interaction between the host and guest molecules of the complexes is dominated by dispersion attraction, and is characterized by typical π-π stacking formed by the interaction between the radial conjugated πsystem of OPP and the in-plane π-electrons of C 18 . In contrast, the intermolecular electrostatic interaction is weak, and covalent and induction effects from orbital interaction is nearly negligible. The in-plane rotational energy barrier of C 18 in OPP is so small that a rapid relative rotation between them seems possible. Classical MD confirmed the molecular self-assembly process of the complexes and the ultrafast rotation behavior of C 18 in OPP, and then described the thermodynamic stability of the molecular nanorotator at different temperatures.