Abstract A new Schiff base ligand N-(2-hydroxy-1-naphthaldehyde)-1,8-diaminonaphthalene (NHND) was synthesized and characterized, and a new ternary photoluminescence enhancement system Eu–NHND–1,10-phenanthroline in acetonitrile was successfully developed to determine trace amounts of Eu3+. The excitation and emission wavelengths were 274 and 617nm, respectively. Under optimal conditions, the photoluminescence intensities of the system showed a linear response toward Eu3+ in the range of 7.0×10−8 to 3.2×10−6M with a detection limit of 7.5×10−9M. The interferences of other trivalent lanthanides and some common ions were described. The system was applied to determine the trace amounts of Eu3+ in a high purity Gd2O3 matrix and in a synthetic rare earth oxide mixture, and satisfactory results proved applicability of the system. Mechanism of energy transfer and photoluminescence enhancement was also studied.