The cryogenic phase behaviors and Raman spectra for D₂O/H₂O-NaCl solutions were observed and measured at temperatures down to 173.15 K. The (ice + hydrohalite) eutectic temperature of D₂O-NaCl solutions is similar to 255.95 K, 4 K higher than that of H₂O-NaCl solutions. On the Raman spectral patterns, the four characteristic peaks of NaCl₂D(₂)O hydrohalite are displayed to be more scattered than those of NaCl₂H(₂)O. The third peak is easier to appear for NaCl₂D(₂)O than for NaCl₂H(₂)O that more cooling-heating runs and higher NaCl concentration are needed for this peak of NaCl₂H(₂)O to be prominent, which indicates that NaCl₂D(₂)O crystallizes more easily than NaCl₂H(₂)O. We assign the 1st peak to the OD/OH stretch vibration of local water, and assign the 2nd, 3rd and 4th peaks to the OD/OH stretch vibrations of coordinating water respectively with D₂O/H₂ONa⁺, Cl-D₂O/H₂ONa⁺, and (Cl-)(₂)D₂O/H₂ONa⁺ interaction configurations. The harder crystallization of hydrohalite and lower eutectic temperature for NaCl₂H(₂)O than for NaCl₂D(₂)O are ascribed to the O-DCl- > O-HCl- and O-DO > O-HO hydrogen bonding interactions.