Objective: To study the effect on alkaloids in Strychnos nux- vomical L. by different decocting time and compatibility dosages of Radix Glycyrrhizae. Methods: To determine the contents of alkaloids with high performance liquid chromatogram( HPLC). Results: There was higher correlation between the contents of alkaloids and decocting time,or compatibility dosage of Radix Glycyrrhizae. The experimental results demonstrated that the number of alkaloids all declined in combined Strychnos nux-vomical L. with Radi...