The photoacoustic spectra(PAS) of the coprecipitates Tb3+-Gd3+-Sal complexes are reported. With the increase of the concentration of Gd3+ion, the PA intensity of complexes decrease firstly, then increase. It is indicated that the addition of the second rare earth ion Gd3+changes the relaxation processes of the complexes. The changes of the fluorescence spectra turn out complementary to the PAS. The intramolecular energy transfer and the intermolecular energy transfer processes in coprecipitates are discussed.