We demonstrated a novel square hybrid nanosheet with a ultrathin thickness for the first time, which was fabricated by self-assembly of hyperbranched poly(ether amine) (hPEA526) containing anthracene (AN) moieties and heptaisobutyl polyhedral oligomeric silsesquioxane (POSS). TEM and AFM images reveal that the average edge length and thickness of the hybrid nanosheets formed by HP1 is 1.2 +/- 0.2 mu m and 4.5 +/- 0.5 nm, respectively. POSS prefers the ordered crystallized aggregation in the formation of the regular square nanosheets, which is confirmed by WAXD and DSC studies. Moreover, these nanosheets are cross-linked through dimerization of anthracene moieties which makes the nanosheets more stable. The other functional moieties such as naphthalene, pyrene, and dodecane can also be easily introduced into the hybrid nanosheets through the same way. The obtained hybrid nanosheets exhibit the multiresponses to temperature and pH, and their dispersion in water can be controlled by temperature. The fluorescence of the hybrid nanosheets decreases with the increasing temperature and pH. The discovery of the hybrid nanosheets is believed to provide a potential guiding significance on the preparation of the functional nanosheets by self-assembly of polymers.