A new kind of europium-organic complex Eu(tta)4 ·DEASP was synthesized, in which the cation DEASP can play the role of two-photon sensitizer for Eu3+. The two-photon sensitization wavelength of Eu3+was extended to 1.06 μm. Furthermore, a series ramification of DEASP were synthesized. The analysis on the structure-property relationships demonstrated the following results. Changing the cation only by substituting the terminal donor group, the two-photon sensitization efficiency can be improved evidently. And, this kind of europium complex can be hopefully applied in the field of biological imaging.