The invention discloses preparation of a supermolecule gel factor based on three-column [5] aromatic hydrocarbon. The supermolecule gel factor is a complex organic gel factor which is synthesized fromamide modified column [5] aromatic hydrocarbon and trimesoyl chloride through a nucleophilic substitution reaction and is based on column aromatic hydrocarbon. According to the gel factor, blue organic gel with aggregation state induction florescence can be formed in cyclohexanol through C-H...pi,pi...pi accumulation and Van der Waals' force. In the organic gel, water solutions of Hg<2+>, Ca<2+>,Mg<2+>, Ni<2+>, Cr<3+>, Cd<2+>, Pb<2+>, Ag<+>, Zn<2+>, Ba<2+>, La<3+>, La<3+>, Eu<3+> and Tb<3+> are respectively added, only addition of Hg<2+> can quench blue florescence of the organic gel, and addition of other cationic ions does not remarkably influence fluorescence intensity of the organic gel, so that specific fluorescence detection on Hg<2+> can be achieved, and a detection limit is 1.02*10<-8>M.