The invention discloses a single conducting wire tension change simulation calculation method and a simulation test device of a transmission line. The simulation test device comprises a curve-shaped track, a fixed pulley at an upper end of the track, a movable pulley arranged on the track and rolling along the track, and a conducting wire towing the movable pulley to roll through the fixed pulley,the conducting wire is connected with a tension meter and a displacement meter, a conducting wire tension simulation weight is hanged on the movable pulley, the simulation test device disclosed by the invention can simulate and shorten a transmission line with a span greater than hectometer to several meter according to the change of factors such as the model number of the conducting wire, the span of the conducting wire and the like, in order to effectively and accurately reflect the tension change of the corresponding transmission line while guaranteeing the consistency of the stress features of a suspension string and the original transmission line, ensure the accuracy and reliability of designing the transmission line and greatly reduce the test difficulty, the test risks and the testcost.