Abstract: In order to optimize the properties of Ti-13Zr-21Cu-9Ni brazing fillers and obtain a good performance Ti alloy joint, rare earth element LaNd was added to Ti-13Zr-21Cu-9Ni brazing fillers. The commonly used TC4 alloy was used as the mother The effect of rare earth element LaNd on the spreading performance of Ti-13Zr-21Cu-9Ni brazing fillers and the performance of TC4 joints was studied by vacuum furnace, field emission scanning electron microscope, X-ray diffractometer and other equipment. The results showed that the spread area of Ti-13Zr-21Cu-9Ni-xLaNd brazing fillers and the shear strength of Ti-13Zr-21Cu-9Ni-xLaNd/TC4 brazed joints first increased and then decreased with the addition of LaNd increased. When the LaNd addition is 0.3%, Ti-13Zr-21Cu-9Ni-xLaNd brazing fillers has the largest spreading area, the maximum value is 0.74 cm², which is 88.8% higher than the matrix; when the addition of LaNd continues to increase, the formed Cu₅La phase greatly reduce the spreading performance of the brazing fillers. Ti-13Zr-21Cu-9Ni-xLaNd/TC4 brazed joint shear strength reaches the maximum when the LaNd addition is 0.3%, which is 157.1 MPa, which is 45.2% higher than the matrix. Therefore, the optimal addition of LaNd It should be around 0.3%.