Seasonal abundance and activity of all the three post-embryogenic stages of Haemaphysalis longicornis, both feeding and free-living phases, were evaluated over a period of 2 years, from February 2008 to January 2010, in North China. Feeding ticks were removed weekly from head and ears of domestic sheep and the attachment sites of this tick were assessed co-instantaneously; free-living ticks were collected weekly in four habitat types by flag-dragging. The results suggested that H. longicornis mainly resides in shrubs and completes one generation per year with population attrition between stages. Infestation of nymphs was detected from March to September with highest peak between late April and early May; adults were detected from April to September with highest peak between late June and July, and an overwintering male population was found during late September to March; infestation of larvae was observed from June to October and peaked between middle August and early September. Most of this tick (91%) attached to head and ears of hosts. Additionally, we captured rodents from April to September 2008, but only a negligible number of nymphs were detected. This result suggested that rodents are not the principal hosts for this tick in the study area.