A field experiment was carried out of interplanting forage grasses (Trifolium repens Linn., Vulpia myuros C. and Lolium perenne L. ) in a two-year old ‘Fuji’ apple (M. domestica Borkh. cv. Red Fuji/ Malus hupehensis Rehd. ) orchard to explore effects of grass interplantation on growth of the apple trees, and utilization, loss and residue of nitrogen in the 0~60 cm soil layer of the orchard, using the ¹⁵N-labeled tracer method. Results show that compared with the apple trees in the plot without grasses interplanted, the trees in the plot with grasses interplanted were found to have an increasing trend in total fresh weight of a plant, thickness and length of new shoots and root-shoot ratio; The effect on root length, roots length density and roots surface area of apple trees was the most significant in the plot interplanted with Trifolium repens Linn., which was followed by the plot with Vulpia myuros C. and the plot with only apple the last; Nitrogen utilization rate also varied sharply between plots, being the highest in the plot with Trifolium repens Linn, which was followed by the plot with Vulpia myuros C. and the plot with only apple in the end; In the plots interplanted with herbage ¹⁵N residue was found mainly in the 0~20 cm soil layer, and higher in content than that in the 0~20 cm soil layer in the plot of apple only. However, the amount soil of residual ¹⁵N in the 20~40 cm and 40~60 cm soil layers was the highest in the plot with apple only, which was followed by the plot with Lolium perenne L., and the plot with Trifolium repens Linn. in the end. In terms of nitrogen loss rate, the four plots displayed an order of apple only > Lolium perenne L. > Vulpia myuros C. > Trifolium repens Linn.. In short, all the findings indicate that planting Trifolium repens Linn., Vulpia myuros C. and Lolium perenne L. in apple orchards improves nitrogen utilization rate and consequently reduces nitrogen loss rate by a certain degree.