Near infrared (NIR) spectroscopy assignment of Magnolol was performed using deuterated chloroform solvent and two-dimensional correlation spectroscopy (2D-COS) technology.According to the synchronous spectra of deuterated chloroform solvent and Magnolol,1　365~1　455,1　600~1　720,2　000~2　181 and 2　275~2　465 nm were the characteristic absorption of Magnolol.Connected with the structure of Magnolol,1　440 nm was the stretching vibration of phenolic group O—H,1　679 nm was the stretching vibration of aryl and methyl which connected with aryl,2　117,2　304,2　339 and 2　370　nm were the combination of the stretching vibration,bending vibration and deformation vibration for aryl C—H,2　445 nm were the bending vibration of methyl which linked with aryl group,these bands attribut to the characteristics of Magnolol.Huoxiangzhengqi Oral Liduid was adopted to study the Magnolol,the characteristic band by spectral assignment and the band by interval Partial Least Squares (iPLS) and Synergy interval Partial Least Squares (SiPLS) were used to establish Partial Least Squares (PLS) quantitative model,the coefficient of determination R2cal and R2pre were greater than 0.99,the Root Mean of Square Error of Calibration (RMSEC),Root Mean of Square Error of Cross Validation (RMSECV) and Root Mean of Square Error of Prediction(RMSEP) were very small.It indicated that the characteristic band by spectral assignment has the same results with the Chemometrics in PLS model.It provided a reference for NIR spectral assignment of chemical compositions in Chinese Materia Medica,and the band filters of NIR were interpreted.