In this study, the Raman and fluorescence spectra of LaCl3 solution were studied with theoretical calculation and spectroscopic experiments. Based on B3LYP method of density functional theory, with the 6-31G(D,P)+Def2-SV (P) based on the group level the lanthanum chloride solution of micro cluster structure is calculated. The results show that the micro cluster molecules tend to form a 9 coordination structure, which verifies the feasibility of the method. Theoretical and experimental Raman values are compared to the basic consistent. The addition of LaCl3 leads to the increase of the peak intensity of the Raman spectra in the 300~600 cm-1 range, which may be caused by the superposition of the La-O vibration and the rocking peaks of O—H in aqueous solutions; In the 3 000~4 000 cm-1 range, the peak of lanthanum chloride solution is narrow compared with water, which may be caused by the stretching vibration of O—H in lanthanum hydrate. Fluorescence emission spectra at 350 nm appear obvious new peak, the good linearity was obtained between the peak intensity and the concentrations, and a rapid method for the quantitative analysis of lanthanum chloride solution from the angle of the complex is also realized. On the same basis set level calculated fluorescence emission center of clusters, in the range of allowable error, the theoretical calculation and the experimental spectra are basically consistent, and the new peak of the experimental spectra are identified.