In order to evaluate the effects of nanoselenium on growth, mineral element contents and quality characteristics of purple potatoes, in this study we treated the purple potato cultivar ‘black beauty’ under hydroponic cultivation with foliarspraying of different concentrations of nanoselenium (0, 0.38, 0.19 and 0.095 mmol/L). The results showed that: (1) biomass and tuber number per plant of all selenium treatments increased significantly compared with the control group, among which the highest increase of plant biomass under the treatment of spraying with 0.095 mmol/L selenium reached 1.5 times, and the tuber number per plant treated with spraying with 0.19 mmol/L selenium significantly increased by 2.2 times. (2) Nanoselenium could significantly improve the selenium content of leaves, roots and tubers of purple potatoes. The pattern of total Se concentration in different tissues of the plant followed the order of root>leaf>tuber, and the total selenium content in tubers reached 0.106 mg/kg under the treatment of spraying with 0.095 mmol/L selenium, which was significantly increased by 0.65 times compared with the control group, that is to meet seriched standard of potato tubers. Meanwhile, the distribution of K, Ca, Mg, Mn and Zn in potato tissues can be controlled by nanoselenium to different levels. (3) With the increase of selenium concentration in foliarspraying, the contents of starch, soluble protein and free amino acid in purple potato tubers were appeared the trend of unimodal trend, which reached the maximum value under 0.19 mmol/L selenium treatment, and increased significantly by 56.33%, 26.91% and 27.89% respectively compared with the control. Meanwhile, the contents of anthocyanin and soluble sugar in tubers showed a decreasing trend, which reached the maximum value under the treatment of spraying with 0.095 mmol/L selenium, and increased significantly by 24.73% and 25.33% respectively compared with the control; while the nitrate nitrogen content was on the rise, and decreased significantly by 34.82% compared with the control, which reached the minimum value under 0.095 mmol/L selenium treatment. Therefore, nanoselenium foliarspraying concentration at 0.095-0.19 mmol/L could significantly promote the growth and increase selenium content and quality characteristics of purple potato.