Rhizoma Corydalis was first recorded in Ben cao shi yi (A Supplement to Materia Medica). In the Tang and Song Dynasties, Rhizoma Corydalis used was derived from Corydalis turtschaninovii Bess. grown in the Northeast China. After the Ming Dynasty, the producing area migrated to the South and Rhizoma Corydalis was replaced by the"Maoshan Rhizoma Corydalis", that is Corydalis yanhusuo W. T. Wang nowadays, and those produced in Jiangsu and Zhejiang areas were recognized as the authentic ones. The collected time of Rhizoma Corydalis was also changed from fall to the beginning of summer. And then the processing methods in the production places underwent a change from the "critical dry", "shade dry" to the modern "boiling" method. In addition, the evaluation of quality of this medicinal was gradually changed from the location of its origin to its medicinal properties.