Abstract: The response of cathead-type transmission towers under the coupling loading of ice and broken wire were studied by using arc length method. The correlative development of bearing capacity, the development and distribution of inner forces, the stress and out-of-plane deformation of braces were analyzed. The effect of ice thickness on the bearing capacities and failure modes of various types of cathead-type transmission towers were investigated. The results indicated that when the transmission towers were under the coupling load of broken wire and icing, the yielding of the column on the compression side and the members at stiffness mutation part were induced by the bending of towers; The internal force between the tower head and top diaphragm was relatively large when the tower body was subjected to torsion, resulting in yielding to the lower diagonal materials. the column yielding on the compression side of the tower botton combining with the brace buckling on the tower body were triggered by the torsion-bending of towers. The increase of self weight of the tower after being covered with ice would exacerbate the bucking of main materials on the compression side and the yielding of braces, reducing the lateral resistance of towers under broken wire load. The coupling of ice and broken wire loads should be taken into account in the design of transmission towers.