M9T337 apple seedlings were used to study the effects of different organic materials and their combination on plant growth, nitrogen utilization and soil properties by using the ¹⁵N isotope tracer technique. There were 8 treatments:CK (chemical fertilizer), S (straw), B (biochar), F (cow dung), SB (1/2 straw + 1/2 biochar), SF (1/2 straw + 1/2 cow dung), FB (1/2 cow dung + 1/2 biochar), SFB (1/3 straw + 1/3 cow dung + 1/3 biochar). The results showed that the application of organic materials promoted the growth of apple seedlings, and SFB treatment had the best fresh weight, height, stem diameter, leaf area and root activity, which were significantly higher than CK and the treatment of single organic materials. The application of organic materials decreased soil bulk density, increased soil total porosity and soil moisture content. The soil bulk density and total porosity under the combined application of biochar were better. During the treatment period, the soil mineralized nitrogen contents, the soil enzymes activities and microbial population under the treatments with mixed organic materials were better than those under the treatments with organic materials alone. Compared with CK and the single organic materials, the combined application of organic materials significantly improved the ¹⁵N utilization rate of apple seedlings and ¹⁵N residual rate in soils, reduced the ¹⁵N loss rate and the SFB treatment had the best effect. According to the comprehensive analysis, the application of different organic materials could promote the growth of apple seedlings, improve soil properties, and improve the absorption and utilization of ¹⁵N, among which the combined application of cow dung, straw and biochar (SFB treatment) had the best effect. These findings could provide a basis for the application of organic materials in apple orchard for the soil quality improvement and fertilizer reduction and efficiency.