Red peony root: it is a kind of circular slice or oblique slice, 0.5 ~ 3cm in diameter and 0.3 ~ 0.5cm in thickness. The surface is powdery white or pink, the center has radial grain, the skin part is narrow, some have fissure. The perimeter is taupe. It's hard and crisp. Taste slightly bitter. The content of paeoniflorin (C23H28O11) should not be less than 1.5% as determined by the above method.