Fire, as a significant driver in shaping habitat use and interspecific interactions among large herbivores in forest ecosystems, is influenced by variations in spatial and temporal scales, as well as by the vegetation community succession following fire disturbances. To unravel the impact of fire disturbances on habitat use and interspecific interactions of sympatric deer species, such as roe deer and moose, a comprehensive study was conducted from 2018 to 2022 in the Hanma National Nature Reserve located in the Greater Khingan Mountains. In both fire-disturbed and non-fire-disturbed areas, infrared cameras were strategically grid-placed to collect detailed data on the activities and behaviors of roe deer and moose. Utilizing the Random Encounter and Staying Time Model (REST), the study aimed to analyze population density differences between roe deer and moose in fire-disturbed and non-fire-disturbed areas; Additionally, the Habitat Selection Strategies of roe deer and moose were assessed using the Univariate Optimal Scale Selection technique and the Linear Mixed Effects Model (LMM), Furthermore, by employing the Levins' ecological niche overlap index, we can assess the impact of fire disturbances on the temporal scale on the ecological niche of roe deer and moose. The results of the study revealed distinct differences in the habitat use patterns between roe deer and moose, The findings indicated that roe deer favored low-elevation areas with gentle slopes in birch forests, while moose showed a preference for habitats near rivers, Interestingly, the distance from fire-disturbed areas emerged as a significant factor influencing the habitat use differences between the two species. In fire-disturbed regions, the succession time had minimal impact on roe deer, whereas moose exhibited a clear preference for post-fire disturbed areas. With the increasing interval between fire disturbances, vegetation succession is progressing, leading to a gradual reduction in the overlap of ecological niches between roe deer and moose, The ecological niche overlap index tends to stabilize. Notably, moose demonstrated a significantly narrower spatial ecological niche width compared to roe deer in fire-disturbed areas, indicating a pronounced species niche differentiation. Consequently, the study highlighted that fire disturbances will to some extent affect interspecies competition between roe deer and moose, ultimately influencing their stable coexistence. These findings provide valuable insights for future forest fire management strategies and conservation efforts aimed at protecting wild ungulate habitats. It underscores the necessity of incorporating fire disturbances into wildlife conservation practices for the sustainable coexistence of these large herbivores in forest ecosystems.