To explore the niche characteristics of parasitic fleas on the body surface of small mammals in Deqin County, Diqing prefecture in the northwest Tibetan of Yunnan province. Forty-two survey sites were selected in Deqin County, classifying into 4 habitats and 5 vertical gradients according to natural environmental characteristics including altitude and topography. The night-clamp method and cage-day method were used to capture the small mammals, and parasitic fleas on their body surface were combed and picked up. The niche characteristics were analyzed by niche breadth (B_i) and niche overlap index (NO). The results indicated that a total of 1275 fleas were collected on small mammals belonging to 33 species of 17 genera in 9 subfamilies of 4 families, in which Ctenophthalmus (Sinoctenophthalmus) yunnanus and Frontopsylla (Frontopsylla) diqingensis were dominant species and there were 12 common species and 19 rare species. On the altitude resource axis, the top three B_i values were Neopsylla specialis dechingensis 0.698, Frontopsylla (Frontopsylla) spadix spadix 0.690, and Neopsylla stevensi sichuanyunnana 0.667, while the top three B_i values on the habitat resource axis were Macrostylophora euteles 0.630, Neopsylla specialis specialis 0.57, Neopsylla specialis dechingensis 0.537, as well as Paradoxopsylla custodis 0.584, Frontopsylla(Frontopsylla)diqingensis 0.567, Frontopsylla(Frontopsylla)spadix spadix 0.553 were the top three B_i values on the host resource axis. From the perspective of multi-dimensional niche width, the B_i values of Neopsylla specialis dechingensis and Frontopsylla (Frontopsylla) diqingensis were larger, which were 1.031 and 1.019, respectively. For the niche overlap index of altitude, habitat and host, significant overlapping species pairs accounted for 35.6%, 39.39% and 9.28%, respectively. Non-overlapping pairs occupied with 26.89%, 18.56% and 51.14%, while fully overlapping pairs accounted for 2.27%, 13.26% and 0.19%, respectively. Among the three ecological factors, the dominant species and common species presented larger niche breadth and stronger ability of competitiveness and utilization of resources. The pattern of niche overlap index of different ecological factors was various, being related to the resource axes. The proportion of significant overlapping and non-overlapping pairs were higher. The former was mostly the overlap between the dominant species, common species and rare species, while the latter mainly formed between rare species. The higher overlap index showed more intense competition, while non-overlap meant no competition in resource utilization. In general, Deqin County has abundant species of parasitic fleas on the body surface of small mammals, and the niche differentiation was relatively uniform. The study provided ecological basis for monitoring, prevention and control of flea-borne diseases in this area.