The utility model relates to the technical field of high-voltage alternating-current isolating switches and specifically relates to a box-type transmission device of a high-voltage alternating-current isolating switch. The box-type transmission device comprises a transmission crank arm, a clamping connection rod, a driving transmission shaft and a driven transmission shaft which are arranged in a box body, wherein the driving transmission shaft and the driven transmission shaft are installed on the box body through composite shaft sleeves, one end of the transmission crank arm is connected with an operating mechanism and the other end of the transmission crank arm is connected with the driving transmission shaft through the clamping connection rod, the two ends of the clamping connection rod are respectively equipped with a joint bearing, the upper part inside the box body is further provided with a balancing connection rod, one end of the balancing connection rod is hinged with the driving transmission shaft and the other end of the balancing connection rod is connected to the right side of the box body through a tension spring, the two ends of a transmission connection rod are respectively equipped with a positive and negative wire joint, and the transmission connection rod is respectively connected with the driving transmission shaft and the driven transmission shaft through the positive and negative wire joints. The box-type transmission device of the high-voltage alternating-current isolating switch has the characteristics of being reasonable in structure, anti-vibration, smooth in transmission and capable of avoiding transmission clamping stagnation.