Salt lake is a natural complex system coexisting with water and salts. Borate species in salt lakes and their distributions are complicated than the pure borate solution. Generally, polyborates can be formed in brine by polymerization during the concentration process. Thus, borates in concentrated brine have a severe supersaturation behavior, which cannot favour the salt lake resource separation between boron and other slats. Therefore, the study of the poly borates distributions in the salt lake brine and their transformation mechanisms is of great importance. Laser Raman spectroscopy is characteristic of in-situ, non-destructive and weak water interference and thus has been widely used to determine borate structure in aqueous solutions. Recently, the modern Quantitative Raman technology with Chemometrics has become an efficient method to accurately acquire the number of matters in a complex system. It shows great advantages in solving spectral problems such as spectral overlap, background interference and baseline drifting and has been widely and deeply applied in the analysis field. Based on the Chemometrics, this paper has studied the quantitative analysis of monoboartes in aqueous solutions by Raman technology, with the three regression models as internal standard, multi-linear regression and partial least squares regression. Also, it has evaluated the three models by using the external standard sample. It was found that both multi-linear regression and partial least squares models had a more accurate amount prediction of the sample, with a relative error of less than 1%. However, the former model shows better values at lower boron concentration. Furthermore, based on the multiple linear regression models, we also explored the borate species and its distribution in the oilfield brine in the west of Qaidam Basin by Raman spectroscopy. The results showed that only the boric acid peak at 875 cm^-1 was detected in the oilfield brine during the evaporation process. The amount of boric acid predicted by the multiple linear regression models agrees well with the boric acid concentration measured using the titration method. The relative error between them is less than 5%. It indicates that the major form of borate in the oilfield is boric acid, and other borate species can be ignored, which explains why the boric acid solid is the only borate saltthroughout the whole oilfield brine crystallization process. The results of this study could provide fundamental information and theoretical guidancefor the future exploration of the quantitative analysis of the borate speciation in the brine under dynamic environmental conditions.