Abstract: In order to improve the solid phase additive manufacturing performance of aerospace high strength and toughness 2219-T8 aluminum alloy, single-channel multi-layer deposition parts with interlayer spacing of 1 mm, 1.5 mm and 2 mm were prepared by friction stir deposition process in this study. The effects of interlayer spacing on the microstructure and mechanical properties of the deposited parts were analyzed. The results show that when the interlayer spacing was reduced from 2 mm to 1 mm, the dense defect-free area of the deposited part was expanded from 24.5 mm to 33 mm, and the material bonding was more sufficient. At the same time, the grains of the deposited parts were obviously refined, and the average grain size was reduced from 3.69 μm to 2.27 μm. The hardness of the deposited parts did not change significantly, and the overall hardness gradient increased, but the homogeneity was better. The tensile strength and elongation of the deposited parts in the construction direction increased by 26 MPa and 3 %, respectively, while the longitudinal mechanical properties did not change much. When the interlayer spacing was 1 mm, the deposited parts show the best material properties, the yield strength was 122 MPa, the tensile strength was 207 MPa, the elongation after fracture was 7%, and the average hardness was 75.6 HV.