Abstract: A homogeneous generalized yield function is developed for equal angle section, based on which the element bearing ratio is defined for thin-walled angle members. The Elastic Modulus Reduced Method (EMRM) for evaluation of ultimate bearing capacity of transmission tower fabricated with angle section is presented, in which the threshold is defined based on the uniformity of element bearing ratio for reduction of elastic modulus of elements with high bearing ratio, and the elastic modulus adjustment strategy is built in terms of the principle of strain energy conservation. The plastic failure mechanism and the ultimate bearing capacity of transmission towers can be given by the proposed method. The limitations of the traditional EMRM and other elastic modulus adjustment procedures in accuracy and robustness, which are resulted from non-proportional loading, are avoided, while their advantages of simplicity and fast convergence are inherited.