In order to investigate the chemical and pharmacological characterization of crude drug processing, the triterpenoidal constituents of Glycyrrhizae Radix(GR) were examined. Processed GR has been often used to reinforce and change the efficacy of GR. Glycyrrhizin(GL) is one of the main constituents of GR. Following procedure described in the oriental medicinal reference, GR and GL were heated at $140^{circ}C{sim}240^{circ}C$ in GC oven. And then, the content of GL in the processed GR and GL was analyzed by HPLC. GL was transformed to $18-{eta}-glycyrrhetic;acid;mono-{eta}-D-glucuronide(GM)$ and glycyrrhetic acid(GA) by processing at $170^{circ}C$. Determination of the content of GL increasing the heating temperature showed that GL was decomposed by heat above $150^{circ}C$. It was also found that the content of GL in GR processed by heat above $170^{circ}C$ remakeably decreased.