In order to investigate the effects of nitrogen nutrient environment changes on the morphology of fine roots in permafrost peatlands, we conducted a nitrogen additions field experiment in the Daxing'an Mountains, Northeast China. Four levels of N treatments were applied including 0 g N m^-2 a^-1 (CK), 6 g N m^-2 a^-1 (N1), 12 g N m^-2 a^-1 (N2), and 24 g N m^-2 a^-1 (N3). In August and September 2020, minirhizotron observation method was applied to monitor the morphology of fine roots in different depths (0-20 cm, 20-40 cm), and the root characteristics were analyzed by WinRHIZO software. The results showed that the total root length, total surface area, total volume and root length density of plant fine roots in the surface peat layer (0-20 cm) were increased with the increase of nitrogen application. In August, the total root length, total surface area, total volume and root length density in N3 treatment were significantly higher than those in other treatments, while in N2 treatment, total surface area and total volume of fine roots were significantly higher than those in control group and N1 treatment (P< 0.05). In September, the total root length and root length density in N3 treatment were significantly higher than those in control group, and the total surface area and total volume of fine roots in N3 treatment were significantly higher than those in control group and N1 treatment (P< 0.05). The results show that nitrogen additions can relieve the nitrogen limitation of plants and can significantly promote the growth of fine roots in the surface peat layer (0-20 cm), but the influence of fine root growth in subsurface layer (20-40 cm) is less than that in the surface peat layer.