To determine whether H. longicornis and D. nuttalli can serve the transmission of Lyme disease as potential vector ticks in North China, the ability of H. longicornis and D. nuttalli to transmit Lyme spirochetes transstadially was estimated under laboratory conditions with vector tick I. persulcatus as control. Results suggest that the two tick species can also acquire active Lyme spirochetes by feeding on infected KM mice. However, they vary in their ability to maintain spirochetes. Only I. persulcatus can maintain active spirochetes during molting, with subsequent tick stages infectious to innocent KM mice. Haemaphysalis longicornis and D. nuttalli maintain spirochetes no longer than the digestion period of blood; after molting, no spirochetes were detected in both of the two tick species. Therefore, both of the two tick species cant be considered as vector ticks, the presence of spirochetes in H. longicornis and D. nuttalli may be tied to co-feeding with I. persulcatus.