Abstract: Comparing of the chemical constituents in the petyoleum solution of Rhizoma Atractylodis and in the petyoleum solution of Corteex Phellodendri with the chemical constituents in the petyoleum solution of Er Miao Pills are obtained by GC/MS, The results show that the chemical constituents of pills made of Rhizoma Atractylodis and Corteex Phellodendri are not simply combined together with chemical constituents of Rhizoma Atractylodis and Corteex Phellodendri. The quantitative of some chemical constituents such as γ-Selinene and Compound No.8 are reduced, another chemical constituents such as β-Eudesmol , β-Elemol and Compound No.9 are reduced.