Plant leaves are important organs due to their autotrophism, and plants have evolved diversified leaf protection mechanisms to ensure their survival under unstable and sub-optimal environmental conditions. Leaf morphological plasticity and alterations to leaf structure are commonly observed following exposure to different light illuminations. There has been extensive research on the enhanced UV-B radiation increase at the earth's surface due to ozone and its deleterious effects to leaf structure and crop photosynthesis, but few studies have investigated the effect on potato. In this study, six potato varieties (lines) were grown under 0, 2.5, and 5.0 kJ m^-2 d^-1 of biologically effective UV-B radiation in pots under field conditions to evaluate the general effects of enhanced UV-B radiation on the leaf structure and photosynthesis of different potato genotypes. The results showed that the leaves of most varieties became incrassate to varying degrees, which, with the exception of one variety, led to an increase in total leaf thickness. The stomata, non-glandular and glandular trichome densities significantly increased. The thickness of the cuticle and wax layer on the adaxial surface appeared to have obvious incrassation based on the scanning electron microscope images, and all these morphological responses have been widely recognized as effective ways of improving tolerance or resistance to UV-B radiation. However, the inhibitive and damaging effects of elevated UV-B radiation to epidermal cells have also been observed. These include smaller cell size, an undefined cellular profile, and an atrophic shape due to dehydration. Constitutive stomata and trichome cells showed similar symptoms. The transmission electron microscope images showed that grana thylakoids in mesophyll cells were swollen in shape and the layers had a disordered appearance. Induced plasmolysis and sediments on twisted cell walls were observed in some cells under UV-B radiation stress. In addition, some catalase paracrystalline inclusions were found in some peroxisomes of a few treated cells, but none were found in the control cells, which suggested that accumulated catalase could alleviate the oxidative stress caused by UV-B radiation. However, these adaptations to leaf anatomy and ultrastructure, and changes in physiological responses could not ameliorate all the destructive effects of enhanced UV-B radiation on the leaves of the treated potato varieties. The six varieties showed distinct interspecific differences in their photosynthetic parameters, such as light use efficiency. Half of them (‘Hezuo 88’, ‘Lishu 6’, and ‘Shida 6’) suffered significant photosynthesis inhibition, which led to a serious decline in photosynthetic efficiency. However, the other half (‘21-1’, ‘21-3’, and ‘Zhuanxinwu’) seemed entirely unaffected. Given that the latter three varieties (lines) are landraces in Yunnan Province, they should be more adaptive and tolerant to the locally high UV-B radiation levels that occur in this low-latitude plateau region. Future research needs to investigate underlying adaptive mechanisms at the physiological and molecular levels.