Abstract: Solvation effects of aqueous organic solvents on complexes of Gallium (Ⅲ)-Morin have been investigated by us firstly. It has been proved that in the presence of organic solvents, the sensitivity and selectivity of fluorescent reaction are greatly increased. The fluorescent yield of the solvated complex Ga(Ⅲ)-Morin-MeOH is 0.505. Ahighly sensitive method for the determination of trace Gallium was recommended. The interference of foreign ions was studied. Satisfactory results were obtained in the determination of trace Gallium in pure Berillium and pure Indium. The composition, fluorescent yield, molar absorptivity were measured.