A theoretical calculating method to deal with the along-line torsion response and torsion equivalent static wind load was proposed aiming to the torsion effect of transmission tower. The influence of different torsion modes and coherence functions on the torsion response was analyzed. Aeroelastic model wind tunnel tests were carried out to justify the theoretical results. The calculating methods of gust loading factors considering both the torsion and translational effects were developed. Results show that calculating results of the along-line torsion responses are coincided well with those of the aeroelastic model tests, indicating the rationality of the proposed methods. The horizontal and vertical coherence functions should both be adopted to obtain the torsion response. When wind blows from the along cross arm direction, the theoretical torsion responses are less than those of the aeroelastic model tests, which is due to the signature turbulence induced by the shielding effect of tower members. The torsion magnified factor (TMF) of tower body is small, whereas the TMF of the cross-arm cannot be ignored in which a factor up to 1.1 can be found.