Process for processing prepared rehmannia root

The invention discloses a process for processing prepared rehmannia root. The method includes: firstly steaming raw rehmannia root with saturated steam and collecting the generated rehmannia root juice, performing cooling to 50-65DEG C, extruding the rehmannia root, then introducing saturated steam to conducting steaming and collecting rehmannia root juice; and drying the well steamed prepared rehmannia root for 8-10h, then adding the rehmannia root juice to conduct stewing for 10-16h, and then further performing drying for 40-50h. The prepared rehmannia root processed by the method provided by the invention has a verbascoside content up to 0.040-0.057%, which is significantly higher than the requirement of 0.02% in 2010 edition ''Pharmacopoeia of the people's republic China'', and the processed prepared rehmannia root has stable quality and high qualified rate.