Fagopyrum qiangcai D. Q. Bai and F. wenchuanense J. R. Shao, two new species of Polygonaceae from Wenchuan County, Sichuan Province, China, are described and illustrated. Fagopyrum qiangcai is closely related to F. esculentum Moench based on its leafy base, triangular leaves, and terminal or axillary racemes. The new species differs in having congested nodes at the base of the plant, triangular to oval terminal leaves with bright red veins, dense inflorescences, white punctate adaxial leaf surfaces, and an articulate pedicel. Fagopyrum qiangcai is diploid, 2n = 2x = 16, with a karyotype of 12 metacentric and four submetacentric chromosomes. Fagopyrum wenchuanense is closely related to F. gracilipes (Hemsl.) Dammer ex Diels but differs in its caespitose habit, the plants often with prostrate stems. Its leaves vary from broadly cordate to ovate to hastate or long hastate, the pedicels are basally puberulent, the stamens and pistils are variable in length, and the capsules are ellipsoid-triangular or broadly ovoid-triangular, 3–3.5 × 2.5–3 mm. Fagopyrum wenchuanense is diploid, 2n = 2x = 16, with a karyotype of 16 metacentric chromosomes.