RESUMEN
<p><b>OBJECTIVE</b>To study the change of paeonol and paeoniflorin, the two major active ingredients contained in Cortex Moutan cultivated in Dianjiang county of Chongqing, due to the change of some influence factors, and explore suitable plant conditions and quality cotrol methods of Cortex Moutan.</p><p><b>METHOD</b>Paeonol and paeoniflorin were determined by HPLC in samples from Dianjiang.</p><p><b>RESULT AND CONCLUSION</b>The ratio of paeonol and paeoniflorin in Cortex Moutan was regularly influenced by altitude, the growth years and harvest time. Cortex could be cultivated at altitude of 400 m to 800 m but 600 m is the best aria because of the peak of the percentage composition of paeonol and paeoniflorin at 600 m. The first and middle third of October in the fifth year is the best picking time of Cortex Moutan because of the maximum of the percentage composition of paeonol and paeoniflorin.</p>