Abstract: To explore the effects of different nitrate nitrogen levels (N₀, N₁, N₂, N₃ and N₄ were equivalent to 0, 2.5, 5, 10, 20 mmol·L^{-1 15}NO₃^- -N, respectively) on the growth, photosynthetic characteristics and ¹⁵N absorption, utilization and distribution, Malus hupehensis seedlings were grown in cultural liquid Hoagland by using the ¹⁵N-labeled tracer method. The results showed that the leaf chlorophyll content, leaf area and dry mass in different organs were the highest in N₂ treatment. With the increase of ¹⁵NO₃^- -N application rates, the leaf net photosynthetic rate (P_n)significantly increased but tended to decease when the ¹⁵NO₃^--N concentration exceeded N₂ treatment. In the 20th day after treatment, the root activity, root length, root surface area and number of tips of seedlings in N₂ treatment were significantly higher than those in the other treatments. The distribution ratio of ¹⁵N in different organs was significantly different among those treatments. The relatively balanced distribution ratio of ¹⁵N appeared in N₂ treatment, which the ¹⁵N utilization rate also reached relatively higher level. The total N content and ¹⁵N absorption of seedlings increased at low ¹⁵NO₃^--N concentration, reached the highest value in N₂ treatment with 103.77 and 21.57 mg, and then deceased at high ¹⁵NO₃^--N concentration. At the 12th day after treatment, the leaf nitrate reductase (NR) activity was the highest in N₂ treatment and the lowest in N₄ treatment. The leaf nitrate reductase (NR) activity deceased by 84.9% in N₄ treatment compared with N₂ treatment at the 16th day after treatment. Our findings indicated that the photosynthesis and absorption of nitrate nitrogen were inhibited under low ¹⁵NO₃^--N stress, and the assimilation of nitrate nitrogen and root growth were restrained under too much higher ¹⁵NO₃^--N level, which was not good for the growth, nitrogen absorption and utilization of apple seedlings. The appropriate nitrogen level could promote plant growth, enhance the photosynthesis and also increase the absorption, utilization and distribution of nitrogen.