A series of complexes of Eu(III)/Gd(III) with p-methoxybenzoic acid (POA), α-thenoyltrifluoro- acetone (HTTA) and Phenanthroline (Phen) were synthesized. These complexes were characterized by elemental analysis, IR spectrum, scanning electronic microscope. Their compositions are revealed to be Eu1-xGdx(POA)(TTA)2Phen (x＝0～1). The fluores-cent excitation spectrum of the complex Eu(POA)(TTA)2Phen is different from those of the complexes Eu(TTA)3Phen and Eu(POA)3Phen, and shows a peak position blue shift than that of Eu(TTA)3Phen, which corresponds to the formation of the complex. The fluorescence enhancement of cofluorescence Gd3+ ions to the Eu(III) complexes is clear. The optimum concentration of Gd3+ is 0.4 (molar fraction). The intermolecular energy transfer between Gd(POA)(TTA)2Phen and Eu(POA)(TTA)2Phen appears to be responsible for the fluorescence enhancement of Eu1-xGdx(POA)(TTA)2Phen .