The invention relates to a three-phase common-box arranged electric switch and an intermediate phase conductor assembly thereof. The three-phase common-box arranged electric switch comprises a housing, wherein a three-phase conductor arranged in a straight line is disposed in the housing. The three-phase conductor comprises a middle phase conductor and side phase conductors arranged on the two sides of the middle phase conductor, a middle phase electrified display sensor used for detecting the voltage state of the middle phase conductor is arranged on the housing, and a conductor protruding out of the plane where the three-phase conductor is arranged towards a middle phase electrified display sensor is arranged on the middle phase conductor. The conductor is arranged on the middle phase conductor, so that the distance between the middle phase conductor and the middle phase electrified display sensor is reduced, the interference of the side phase conductor to the middle phase electrified display sensor is prevented, the accurate detection of the middle phase electrified display sensor to the voltage state of the middle phase conductor is realized, the structure is simple, and the large-scale production is facilitated.