In human-dominated landscapes, habitat degradation has led to population and range declines for many species. The sable (Martes zibellina) is a first-class national protected animal in China with an endangered population; therefore, a priority for the conservation management of this species is to carry out habitat suitability research for the development of scientific habitat conservation plans. In this study, activity data for the sable and its prey (lepus timidus) were collected in Beijicun National Nature Reserve, Heilongjiang Province, from January 2021 to the end of August 2022 by conducting line transect surveys, footprint tracking, and infrared camera monitoring. MaxEnt habitat modeling analysis was used to evaluate the habitat suitability for the sable populations at six resolution scales (30m, 60m, 120m, 240m, 480m, and 960m) after resampling using ArcGIS 10.4. Based on the contribution rate of the main habitat variables to the model and their stability effect, and considering the study area comprehensively, we selected a 30 m resolution scale as the optimal scale for the sable habitat analysis; the area under the curve value of the 30m resolution scale habitat prediction model was 0.881. We found that prey resources, vegetation types, and terrain variables were the main variables affecting habitat suitability for the sable. Suitable habitat for the sable was in areas with a high probability of snow rabbits, close to grassland and rivers, approximately 200-400m above sea level, 1.5km from evergreen coniferous forest, approximately 200m from deciduous coniferous forest, and with a slope angle of 50° to 250°. The habitat suitability analysis showed that the area of suitable habitat and semi-suitable habitat for the sable in Beijicun National Nature Reserve was 23.66km, accounting for 17.2% of the reserve. Habitat fragmentation was considerable, and was mainly concentrated in the central, eastern, and northwestern parts of the reserve. Based on our results, we suggest that (1) human activities should be strictly controlled to avoid the continuous expansion of the area of unsuitable habitat caused by human interference; (2) ecological corridors should be established to promote migration of individuals between the western and central populations of the sable in the reserve, so as to reduce the probability of local extinction of the sable populations; (3) fragmented habitat in the eastern region should be restored and the area of suitable habitat in this region should be expanded, and fragmented habitat as a whole should be reconnected. Creating conditions for the recovery of the sable population in the northernmost part of China is of great importance for biodiversity conservation in this region.