Aim:To analyze the volatile chemical components of the herbal pair Rhizoma Ligustici Chuanxiong-Radix Paeoniae Rubra (RLC-RPR) and compare them with those of each of the herbs alone.Methods:Gas chromatography-mass spectrometry (GC-MS) ,a chemometric resolution technique using the heuristic evolving latent projections (HELP) method.and the overall volume integration method were used.Results:In total,52,38,and 61 volatile chemical components in RLC,RPR,and RLC-RPR essential oils were determined,respectively,accounting for 95.14%,95.19%,and 89.68%ofthe total contents ofessential oil ofRLC,RPR,and RLC-RPR,respectively.The majn volatile chemical components were butyldienephthalide (20.65%) and ligustilide (50.15%) for RLC;and n-hexadecanoic acid (20.18%) ,[Z,Z]9,12-octadecadienoic acid (30.11%) ,2-hydroxy-benzaldehyde (17.08%) for RPR,and butyldienephthalide (14.80%) ,and ligustilide (38.91%) for RLC-RPR.The main volatile chemical components of RLC-RPR were almost the same as those of RLC,but the relative amounts were altered.Conclusion:The number of volatile chemical components in RLC-RPR was almost equal to the sum of the number in the 2 constituent herbs.but the relative amounts were altered.Furthermore,an acid-base reaction takes place during the process of decocting the herbs.The data gathered in this study may be helpful for understanding the synergistic nature of this herb pair in traditional Chinese medicine.