[Objectives] Biodiversity monitoring is a core method for assessing the health of ecosystems in nature reserves, while the characteristics of spatiotemporal niche differentiation serve as a key basis for analyzing the coexistence mechanisms of animal communities. Focusing on the Fujian Meihua Mountain National Nature Reserve, this study aims to grasp the current status of mammalian diversity in the reserve and clarify the laws of spatiotemporal niche differentiation of mammalian communities. [Methods] From January 2014 to August 2024, 72 camera traps were deployed across the reserve, covering core, buffer, and experimental zones, with elevations ranging from 800 to 1 800 m and vegetation types including evergreen broad-leaved forests, coniferous-broadleaved mixed forests, and bamboo forests (Fig. 1). The cameras operated continuously, with data collected every three months. Mammal species were identified and classified according to the Illustrated Handbook of Mammals in China (2005) and the 2024 edition of the Catalogue of Mammals in China. For data analysis: 1. The relative abundance index (I_RA) was calculated to evaluate species richness. Species with I_RA ≥ 1 were defined as common species. 2. Diurnal activity rhythms were analyzed via three methods:kernel density estimation (via R packages overlap and activity) to generate activity curves, nocturnality index to classify activity patterns and rose histograms (via Oriana 4 software) to visualize cyclic activity data (Fig. 2). 3. Spatiotemporal niche characteristics were quantified:temporal niche overlap coefficient (Δ) and significance (via Wald test with 1 000 iterations) were calculated by R packages to assess differences in activity rhythms. Spatial niche breadth and overlap index (I) were computed through the Levins’ niche analysis method via R package spaa to evaluate resource utilization strategies among species (Tables 2, 3). [Results] These cameras collectively accumulated 262 944 d of effective operation, during which they captured 25 405 independent and valid events. The infrared cameras recorded a total of 17 mammal species belonging to 12 families of 5 orders. The I_RA of the species followed a descending trend of Muntiacus reevesi (I_RA = 52.44), Sus scrofa (I_RA = 6.42), Niviventer niviventer (I_RA = 4.19), Arctonyx collaris (I_RA = 3.54), Callosciurus erythraeus (I_RA = 2.38), Lepus sinensis (I_RA = 1.96), Macaca thibetana (I_RA = 1.37), and Herpestes urva (I_RA = 1.12), and the other species showed the I_RA less than 1.00 (Table 1). The analysis of activity rhythms for common species (I_RA ≥ 1) indicated that Mu. reevesi, A. collaris, and C. erythraeus were crepuscular with bimodal activity peaks (Mu. reevesi active at 06:00 ~ 08:00 and 16:00 ~ 18:00). S. scrofa, Ma. thibetana, and H. urva were diurnal with single daytime activity peaks. N. lotipes was strictly nocturnal (β = 92.63%), while L. sinensis was nocturnal-leaning (β = 86.36%) (Fig. 2). Spatiotemporal niche overlap analysis revealed that C. erythraeus and N. lotipes had low temporal niche overlap (Δ = 0.34) and moderate spatial niche overlap (I = 0.51). Mu. reevesi and S. scrofa (Δ = 0.85, I = 0.80), Mu. reevesi and A. collaris (Δ = 0.92, I = 0.69), as well as S. scrofa and A. collaris (Δ = 0.83, I = 0.71) all showed high spatiotemporal niche overlap. The spatial niche overlap between L. sinensis and Ma. thibetana was the lowest (I = 0.03) (Fig. 3, Table 2). [Conclusion] The 10-year monitoring reveals that mammals in the Fujian Meihua Mountain National Nature Reserve maintain coexistence through differentiated strategies:temporal partitioning (diurnal C. erythraeus vs. nocturnal N. lotipes), spatial separation (canopy-dwelling Ma. thibetana vs. ground-dwelling L. sinensis), and dietary differentiation (herbivorous Mu. reevesi vs. omnivorous S. scrofa). These findings provide basic data for the protection and management of wild mammal resources in the Fujian Meihua Mountain National Nature Reserve and can offer a scientific basis for long-term biodiversity monitoring and evaluation. At the same time, they are used to explore the current status of spatiotemporal niche distribution patterns of mammals after the disappearance of Panthera tigris ssp. amoyensis.