From 2002 to 2004, in Dahaitou National Natural Reserve, Chi Cheng county, Hebei province, mortality was surveyed for all immature stages of the two coexisting melitaeine butterflies Melitaea phoebe and Euphydryas aurinia for two generations in the same habitat network. Life tables were constructed to explore the effects of the main mortality factors on population dynamics. The results showed that the total mortalities of two generations of M. phoebe (89% in the 2002-2003 generation, and 80% in the 2003-2004 generation) were higher than those of E. aurinia (59% and 72% respectively). For M. phoebe, mortality due to grazing was the most important factor, especially during the post-hibernating larval period. The k  value for grazing was 0.559 and 0.167 respectively during the two generations. Even in the small populations, the parasitoids caused some post-diapause larvae (4% and 9% for the two generations respectively) and pupae (13% and 24%) to death. For E. aurinia, mortality during hibernation was the highest and the k value for the two generations was 0.073 and 0.199 respectively, which was influenced by host plant quality. In contrast, parasitoids had little effect on the population regulation, because only 4% of the post-diapause larvae and 7% of the pupae were dead due to parasitoids in the 2003-2004 generation. These results suggested that different conservation strategies should be taken for the two butterflies. For M. phoebe, to decrease grazing, especially its effects on the source population during the post-hibernating larval group stage, is crucial for its population restoration and growth. For E. aurinia, however, improvement of the host plant quality by habitat managements in breeding areas, which could increase the survivorship during the hibernation period, is helpful for its long-term persistence and conservation.