Abstract: Excessive application of nitrogen (N) fertilizers leads to nitrogen loss and increases the cost of agricultural production. Screening rice cultivars with high N efficiency is an effective approach to improving N use efficiency and reducing environmental pollution. In this paper, hydroponic experiments were conducted to examine the differences in N absorption and accumulation of 55 rice cultivars (lines) at seedling stage. The experiments used the same N dose of 40 mgL1 in the form of both NH₄⁺-N and NO₃^–-N and the evaluation indices standardized using subordinate function of interval 0, 1. The 55 rice cultivars (lines) were classified based on N use efficiency and hierarchical cluster analysis. There were significant differences in aboveground biomass, including whole plant stem, leaf and root, as well as N content in roots, stems and leaves of the rice cultivars (lines) between treated with NH₄⁺-N and NO₃^–-N (P < 0.05). Also the ranges of coefficients of variation were 0.690.80 and 0.570.74, respectively, for NH₄⁺-N and NO₃^–-N treatments. Factor analysis showed that the principal com- ponents of the NH₄⁺-N and NO₃^–-N treatments were the same. The first principal component was mainly reflected biomass indices and N accumulation, determined using the whole plant, stem, leaf and root biomass, as well as accumulated N in the whole plant, stem and leaf and root. The second principal component was determined using N content. By combining variation characteristics and factor analysis of N uptake and accumulation in rice, the whole plant biomass, stem and leaf biomass, root biomass, stem and leaf N accumulation were used as indices to evaluate high N use efficiency potentials of rice cultivars (lines) at seedling stage. Calculation of the comprehensive values of N use efficiency, based on the membership function method and fitted hierarchical clustering chart of squared Euclidean distance, showed that the 55 rice cultivars (lines) grouped into three categories — high, medium and low N use efficiencies. Rice cultivars (lines) with high, medium and low N use efficiencies with NH₄⁺-N and NO₃^–-N treatments accounted for 10.91%, 27.27% and 61.82% of the total rice cultivars (lines), respectively. The whole plant biomass, stem and leaf biomass, root biomass, stem and leaf N accumulation could be used as indices to evaluate the N use efficiency potentials of rice cultivars (lines) at seedling stage. ‘Guangliangyou 3905’, ‘Yongyou 9’, ‘Zhongxian 2503’, ‘Ⅱyou 602’, ‘Liangyou 766’ and ‘Shenliangyou 1813’ rice cultivars had high N use efficiency under both NH₄⁺-N and NO₃^–-N treatments.