Raman spectroscopy, which can provide valuable information about chemical structure, is widely used as an analytical tool for material identification and quantitative chemical/biological analysis. Surface-enhanced Raman spectroscopy (SERS), overcoming the traditional limitation of weak signals, improves the signal intensity significantly. The preprocessing of Raman spectrum is a very useful way to reduce the irrelevant systematic variations in the spectra data while improves the accuracy of further quantitative analysis, which includes de nosing, background correction, normalization and intensity measurement. In this paper, we first describe several commonly used processing methods, then check which processing procedure can provide the best regression analysis of peak intensity. The value of peak intensity is correspondent to the concentration of analyte. According to our experiments for the real Raman spectra data collected from detection on low concentration of Rhodamine and an unique internal standard, the procedure which combines the morphological weighted penalized least square(mpls) algorithm with maximum peak height measurement method achieves the best performance among all the studied processing methods.