Objective The identification of Santali Albi Lignum and its common counterfeits Osyris lanceolata Lignum,Santalum spicatum Lignum was studied to provide experimental basis for the authenticity of this medicinal herb.Methods The identification was carried out using morphological,microscopic,and thin-layer identification methods.The volatile oil of Santali Albi Lignum and its counterfeits were extracted by steam distillation and the volatile oil components were analyzed by gas chromatography-mass spectrometry(GC-MS).The differences of volatile oil components among the three were compared.Results Santali Albi Lignum and its common counterfeits all possessed a sandalwood aroma,but Santali Albi Lignum has abundant oiliness and strong aroma.Osyris lanceolata Lignum aroma exhibits slightly strong odor and slightly camphor flavor,and the smell of Santalum spicatum Lignum is sweet and fragrant.Santali Albi Lignum is greyish-yellow to yellowish-brown in color,while Osyris lanceolata Lignum is generally reddish brown in color,Santalum spicatum Lignum is light yellow to light yellowish-brown,but its surface shows reddish-brown when exposed to air for a long time.In the transection section,the ray width of Santali Albi Lignum is more than 1-2 rows of cells,with occasional 3 rows of cells.The ray width of Osyris lanceolata Lignum is 1-3 rows of cells,while the ray width of Santalum spicatum Lignum is 1-2 rows of cells,mostly uniseriate.In the tangential section,the wood ray of Santali Albi Lignum has a height of 5-15 cells,the wood ray of Osyris lanceolata Lignum has a height of 4-10 cells,while the wood ray of Santalum spicatum Lignum has a height of 4-16 cells.In the radial section,fewer calcium oxalate crystal was found in Santali Albi Lignum,more calcium oxalate crystal was appeared in Osyris lanceolata Lignum,more and larger calcium oxalate crystal was identified in Santalum spicatum Lignum.Genuine and fake sandalwood can be distinguished using sandalwood oil as the thin-layer chromatographic reference.And the volatile oil content of fake Osyris lanceolata Lignum and Santalum spicatum Lignum is lower than that of Santali Albi Lignum.The main components of Santali Albi Lignum are α-santalol and β-santalol.The low content of santalol has been found in Osyris lanceolata Lignum,while α-santalol is extremely low in Santalum spicatum Lignum oil and β-santalol has not been found.Conclusion There are small differences among Santali Albi Lignum and its adulterants in characteristics,microscopical characteristics.But the differences have been found in three-way cross section,thin layer chromatography,volatile oil content and composition characteristics,which can be used for identification of Santali Albi Lignum and its counterfeits.