Abstract: Two pieces of 2 mm-thick IC10 Ni-based single-crystal superalloy were butt welded, and the two plates were filled with GH4169 wire by using vacuum electron beam welding; the microstructure and mechanical properties of the welded joints were analyzed. The results show that the growth direction of grains on the left and right sides of the weld is roughly along the direction of the temperature gradient based on the metallographic morphology. According to the results of EBSD, the grain orientation on the left side of the weld is consistent with that of the base material, namely, single-crystal structure, and the right side of the weld is polycrystalline. After testing the mechanical properties of the nano-twins found in the polycrystal, the maximum tensile strength at 700 ℃ is 762 MPa. The tensile strength of the welded joint is as high as 948 MPa after high-temperature tension, and the mechanical properties of the joint have exceeded those of the base material.