Sugar beet (Beta vulgaris L.), as a salt-tolerant plant, has been widely cultivated in saline-alkali soils, e.g. southern Xinjiang of China, due to its effective capability of reducing soil salinity. A two-year field experiment was conducted on drip-fertigated sugar beet under plastic mulch to explore to effects of three irrigation amounts (W₁: 0.60 ET_c, W₂: 0.80 ET_c and W₃: 1.00 ET_c, where ET_c is the crop evapotranspiration) and six nitrogen application rates (N₁: 25 kg N ha⁻¹, N₂: 60 kg N ha⁻¹, N₃: 120 kg N ha⁻¹, N₄: 240 kg N ha⁻¹, N₅: 360 kg N ha⁻¹ and N₆: 480 kg N ha⁻¹) on sugar beet growth, ash salt accumulation, plant Na⁺, K⁺, Ca²⁺ and Mg²⁺ uptake. The results showed that the year and the two-way interaction of irrigation and nitrogen fertilization had significant effects on dry matter, ash salt accumulation, plant Na⁺, K⁺, Ca²⁺ and Mg²⁺ uptake, but there was no significant effect of the three-way interaction of year, irrigation and nitrogen fertilization on ash salt accumulation, plant Ca²⁺ and Mg²⁺ uptake. The dry matter, ash salt accumulation, Na⁺, K⁺, Ca²⁺ and Mg²⁺ uptake of N₁ were significantly lower than those of other treatments. Nitrogen fertilization increased the dry matter and ash salt accumulation, Na⁺, K⁺, Ca²⁺ and Mg²⁺ uptake of sugar beet. The ash salt, K⁺ and Ca²⁺ were mainly distributed in the leaf and petiole, while Na⁺ and Mg²⁺ were mainly distributed in the taproot. Among the four ions, the average contents of K⁺ and Na⁺ were larger in all treatments, which were 1.79 % and 1.62 % in the two years, respectively. The average content of Mg²⁺ was 0.36 % in all treatments in the two years, and the average content of Ca²⁺ was lowest in all treatments, which was 0.14 % in the two years. Compared to W₁ and W₂, W₃ decreased the dry matter and ash salt accumulation, plant Na⁺, K⁺, Ca²⁺ and Mg²⁺ uptake. The ash salt accumulation, plant Na⁺, K⁺, Ca²⁺ and Mg²⁺ uptake increased with the increasing dry matter accumulation. Based on the response surface methodology, the relationships between water-nitrogen inputs and dry matter, ash salt accumulation, plant Na⁺, K⁺, Ca²⁺ and Mg²⁺ uptake were established. The results can provide a theoretical basis for the phytoremediation of sugar beet in southern Xinjiang of China and maybe elsewhere with similar arid and semi-arid climates.