Polycyclic aromatic hydrocarbons (PAHs) bound to indoor dust pose a significant health threat, while limited studies focused on their difference between rural and urban households, particularly in highland regions. This study systematically analyzed PAHs in indoor dust collected from rural and urban plateau households in Yunan Province, China focusing on their concentrations, particle-size distributions, sources, and carcinogenic risks. Rural households showed significantly higher PAH concentrations than urban households (7575.03 ng/g vs. 5788.73 ng/g), with higher proportion of 2-ring PAHs in urban households and 3–4 ring PAHs dominating in rural samples, reflecting differences in combustion sources and building characteristics. A distinct particle-size pattern of PAHs was also observed, with higher levels in coarse fractions (F1–F3) in urban households, while fine fractions (F4–F6) were enriched in rural households. The results of source apportionment via PMF found that traffic emissions dominated the total incremental lifetime cancer risk (ILCR) in both rural and urban households (57.4% and 64.8%, respectively), followed by biomass burning and/or cooking (25.9% and 22.6%, respectively), and coal burning (16.7 and 12.6%, respectively). Moreover, the overall ILCR in rural households was significantly higher than that in urban households, and children exhibited significantly higher ILCR values than adults in both rural and urban households, with a total ILCR of 4.52×10⁻⁶, primarily via dermal contact and ingestion. These findings provide a scientific basis for identifying and managing indoor air pollution risks in plateau households.