ABSTRACT：Compared to the angle-steel tower, the steel tube tower is much larger in load, height and span. The node design is the key link to ensure the structural safety of steel tube towers. Based on a case study of the large steel tube tower for 1 000 kV UHV(ultra high voltage) lines, a finite element model of the typical K-Joint is established and the mechanical behavior, stress distribution and the elastoplastic failure process of the joint have been studied respectively, which can be referred for design of K-Joints of steel tube towers.