Abstract: Wake-induced galloping is a high risk for a safe operation of electrical transmission system due to dense arrangement of sub-conductors in multi-bundle conductors. To investigate the wake-induced galloping characteristics of eight bundle conductors with extra-high voltage, the variation of aerodynamic forces of each sub-conductor in the eight bundle conductors changing with angle of attack was tested by wind tunnel tests. Because of the wake interaction within sub-conductors, a relatively distinguishable difference can be observed among the aerodynamic forces of the eight conductors. Especially, when a leeward sub-conductor is in the wake of windward sub-conductor, the drag exerted on the leeward conductor significantly drops. The wake-induced galloping of eight bundle conductors with two span-lengths 308m and 405m was numerically simulated by the ABAQUS software. Based on the simulation results, a critical wind speed has been found for the wake-induced galloping. The galloping will not take place when the wind speed is lower than the critical speed. The motion orbit of the sub-conductor is elliptical with wake-induced galloping. Given the same wind speed, the amplitude of the galloping with long span-length is greater than that with short span-length.