Abstract: Taking the Baihetan to Jiangsu ±800 KV transmission line DC tower across the Yangtze River as the engineering background, eight TY-joint specimens were designed and subjected to full-scale tests, and the failure forms, ultimate bearing capacity and deformation of the specimens were obtained. The finite element model was established and compared with the experimental results to verify the correctness of the model. On this basis, the influences of key factors on the mechanical properties of the joints were studied, such as the diameter ratio of the branch to main head, the diameter to thickness ratio of main head, the ratio of ring plate width to main head diameter and the ratio of ring plate thickness to wall thickness of main head. The results of test and finite element analysis show that the internal stiffening structure can significantly improve the ultimate bearing capacity and stiffness of the joint and reduce the local deformation. With the increasing of the diameter ratio of the branch to main head, the main wall thickness, the thickness and the width of ring plate can effectively improve the ultimate bearing capacity of the joint. The simplified mechanical model of TY-joint is established, and the simplified calculation method of ultimate bearing capacity is given. The comparison between the experimental and numerical results shows that the established mechanical model meets the accuracy requirements and can provide a reliable reference for the design of similar joints in engineering.