Paeoniae Radix Alba, a commonly used traditional Chinese medicine derived from the dried roots of Paeonia lactiflora, is mainly produced in Anhui, Zhejiang, Sichuan, Shandong, and Hunan provinces. Since this plant has been cultivated for a long period, various cultivars have been formed in different producing areas. Based on systematic herbal textual research and a review of local chronicles, this study investigated the germplasm resources of medicinal P. lactiflora in the five main producing areas of Paeoniae Radix Alba. Furthermore, it outlined the cultivation history and current status of the germplasm resources of medicinal P. lactiflora in these regions. The results indicated that among the 12 medicinal cultivars of P. lactiflora, 8 cultivars were monopetalous red flowers, which are consistent with the medicinal germplasm highly regarded throughout history in ancient medical books. Additionally, there are cultivars with monopetalous white flowers, polypetalous white flowers, and polypetalous pink flowers in the main producing areas, indicating the rich germplasm resources of medicinal P. lactiflora in China. This paper provides a survey basis for the germplasm conservation and rational resource utilization of high-quality medicinal P. lactiflora.