Abstract:Chinese fir (Cunninghamia lanceolata (Lamb.)Hook) seedlings were raised from seeds and grew in pot culture at six levels of N (urea) supply: 0.0, 0.4, 0.8, 1.2, 1.6 and 2.0gN/pot. The results of the trial are as follows: 1. With increasing levels of N supply from 0.0 to 1.2 gN/pot there were greater height, stem basal diameters, dry weight of leave, stem, root and seedling, numbers of shoots, total lengths of shoots, chlorophyll contents, net photosynthesis rate, respiratory rate, photorespiration rate of seedlings, while with increasing levels of N supply from 1.2 to 2.0gN/pot all of the items decreased. But with increasing levels of N supply there were shorter lengths of roots. 2. There were highly significant positive linear correlation between dry matter weight and net photosynthesis rate, respiratory rate of seedling. And there were highly significant negative linear correlation between dry matter weight and photorespiratory rate of the seedling. 3. With increasing levels of N Supply there were greater total N concentrations of roots, stems, leaves. 4. If the concentration of leaves were in the sub- optimum rangs there were significant positive linear correlation between height, stem basal diameters, dry weight of seedling, net photosynthesis rate, chlorophyll contents of the seedlings and N concentration of leaves, but if the N concentration were in the superoptimum rangs there were significant negative linear correlation.