Double tungstate crystals Nd∶NaGd(WO4)2(Nd∶NGW)and Nd∶NaLa(WO4)2(Nd∶NLW) belong to the tetragonal space group I41/a, is one kind of very promising laser crystal. In this paper Raman spectra of two crystals were analyzed in terms of group space theory. Thirty-six vibration modes were acquired. Therefore, it has thirty-six free degrees. The number of vibration modes is complied with that of the free degree. The polarized Raman spectra were discerned by using two excitation wavelengths (514.5 nm and 785 nm). Although the structure of them are similar, there was a bit discrepancy between Nd∶NaGd(WO4)2 and Nd∶NaLa(WO4)2 of the Raman spectra corresponding to the radius of Nd3+, Gd3+and La3+. Through the comparison of different wavelength excited Raman spectra ,we also got several resonance Raman peaks.