Isotrema jinquanii, a new species of Aristolochiaceae from limestone areas in Guangxi, China is described and illustrated now. This new species is most similar to I. sinoburmanicum in the shape of perianth. The morphological differences from the latter by the stem densely golden-tomentose at young twigs and densely brown-tomentose when aged, the petiole 1.5–3.1 cm long, densely golden (brown)-tomentose, the leaf blade 5.2–10.8 × 2.3–4.4 cm, densely golden (brown)-tomentose abaxially, the bracteole triangular, ca. 1.5 × 1 mm, the perianth outside densely brown-villous, the throat constricted, densely warty inside.