To work out a qualitay standard of Radix Angelicae dahuricae.TLC and HPLC were adopted.Four coumerin compounds were identified by TLC, and the contents of two compounds were determined by HPLC.Imperatorin, isoimperatorin, byakangelicin and oxypeucedaninhydrate can be found simultaneously in Radix Angelicae dahuricae. The contents of imperatorin and isoimperitorin are not lower than 0.1% and 0.04% respectively.