In order to reveal the distribution patterns and causes of microplastics (MPs) in the surface water of plateau lakes with different degrees of human interference, this study selected Shudu Lake, which has relatively weak human interference, and Xingyun Lake, which has relatively strong human interference, as the research areas. Through sample collection and the separation, extraction, and identification of MPs, the distribution characteristics and source differences of MPs in the surface water of the two lakes were compared and analyzed, providing a theoretical basis for the prevention and protection restoration of MPs in different plateau lakes. The results indicate that: (1) The average abundance of MPs was 1.82 particles/m3 in Shudu Lake and 2.14 ± 1.25 particles/m3 in Xingyun Lake. The average number of MPs was 478 ± 57 particles/individual in Shudu Lake and 558 ± 314 particles/individual in Xingyun Lake. As the intensity of human disturbance increases, both the average abundance and average count of MPs in the surface waters of these two plateau lakes show a gradual upward trend. (2) The MPs in Shudu Lake are mainly black and blue (with an average total count of 295 ± 12 particles/individual), while those in Xingyun Lake are mainly blue and black (with an average total count of 403 ± 106 particles/individual). The shapes of MPs in both Xingyun Lake and Shudu Lake are mainly line, with an average number of 462 particles/individual in Shudu Lake and 481 ± 239 particles/individual in Xingyun Lake. The average number of MPs with a size of ≤ 200 μm is 86 ± 30 particles/individual in Shudu Lake and 280 ± 167 particles/individual in Xingyun Lake. The main polymer types in Shudu Lake are 4 types (rayon (RY), polypropylene (PP), polyethylene (PE), and polyethylene terephthalate (PET)), while in Xingyun Lake there are 7 types (RY, PE, PET, low-density styrene-butadiene-styrene (SBS), polyethylenimine ephchlorohydrin modified (PEM), polyester (PES), and polyvinyl alcohol (PVA)). Shudu Lake has fewer polymer types than Xingyun Lake, indicating that the sources of MPs in Xingyun Lake are more diverse. With the increase in the intensity of human interference, the average quantities of the main colors (black and blue), main shapes (line), and size range (≤ 200 μm) of MPs in the surface water of the two plateau lakes have all shown a gradual increase trend, and the number of main polymer types has also shown a gradual increase trend. (3) Shudu Lake is oligotrophic and subject to limited anthropogenic disturbance; the main sources of microplastic pollution are tourism activities, grazing, and atmospheric deposition. Xingyun Lake is mildly eutrophic and experiences stronger human interference; MPs pollution originates from domestic sewage, agricultural cultivation, transportation, fish farming, fishing operations, industrial production, tourism activities, atmospheric deposition, and grazing activities. The distribution and sources of MPs in the surface waters of the two plateau lakes differ, and the level of anthropogenic disturbance is the key factor determining MPs abundance.