In this work, cryolite crystals with a molecular ratio of CR=3 in the NaF-AlF3 binary system were prepared, and a series of aluminum-fluorine cluster structure models were constructed. The micro-confocal Raman spectroscopy detection technology was combined with first-principle theoretical calculations. The author observed and studied the temperature-induced phase transition process of cryolite, and analyzed the Raman characteristic peak positions of anionic clusters such as AlF4-(622-628 cm-1), AlF52-(555-560 cm-1), AlF63-(510-515 cm-1). As for the cryolite molten salt system, by correcting the scattering cross section and splitting the peak of the molten salt experimental Raman spectrum, quantitatively analyzed the microstructure of cryolite molten salt. In the cryolite molten salt, the various anionic clusters have molar percentages of AlF4-(2.7%), AlF52-(25.8%), AlF63-(40.4%), F-(31.3%).