Abstract: A 2-year pot experiment was conducted to study the effects of water and nitrogen additions on the growth and leaf and fine root traits of Alhagi sparsifolia seedlings, and to investigate the functional trait relationships between leaves and fine roots. The experiment was a completely randomized design with three water levels [drought, 30%-35% field capacity (FC); middle water level, (60%-65% FC); high water level, (80%-85% FC)] and four nitrogen (N) levels (no, low, middle, and high N level). The results showed that the biomass and the leaf and fine root traits of A. sparsifolia were significantly affected by the interaction between water and N treatments. However, the responses of different functional traits to water and N differed depending on the plant growth stage. For 1-year-old A. sparsifolia, there was no significant difference in the total root biomass between the drought and low-N treatment (51 mg N/kg) and the middle water treatment, but the total root biomass was higher in both of those treatments than in the other treatments. The maximum values of leaf N concentration (LNC) and specific leaf area (SLA) and the minimum value of leaf tissue density (LTD) were in the drought and middle-N treatment (102 mg N/kg). The maximum specific fine root length (SRL) value and very low fine root tissue density (RTD) values were in the drought and high-N treatment (306 mg N/kg). For 2-year-old A. sparsifolia, the maximum values of leaf, fine root, shoot, and belowground biomass were in the middle water and N-supply treatment. The maximum SLA and minimum LTD were in the control (drought and no N), whereas maximum SRL and very low RTD values were in the drought and low-N treatment. Leaf biomass was significantly and positively correlated with total root biomass at two growth stages, but there was no correlation between leaf and fine root traits. For the same organ, SLA was positively related to LNC, but negatively correlated with LTD. There was a negative correlation between SRL and RTD. The responses of leaf and root traits to different water and N supplies were not synchronized. The linkages between above- and below-ground growth were mainly reflected by the consistent variations in leaf and root biomass.