Abstract: Thin-layer chromatographic scanning (TLCS) was used to determine the content of β-amyrin in Periploca Forrestii Schltr.and to evaluate the quality of this medicine from different origins.The plate adsorbed with a thin layer of silica gel was used as the stationary phase,and mixture of petroleum ether and chloroform (mixed in the ratio of 2 to 3 by vol.) was used both as the mobile phase and as developing solvent.The spot of β-amyrin was separated clearly and determined by single-wavelength linear transmission scanning (SWLTS) at 536 nm.Linear relationship between values of peak area and mass of β-amyrin was kept in the range of 0.39-3.51 μg.Test for recovery was made by standard addition method at 3 mass levels of 0.978,1.220,1.464 μg,and the average values of recovery obtained were 101.3%,96.8%,100.2%,respectively.