The invention provides an auxiliary device for replacing a tubular bus support porcelain insulator. The device is composed of a U-shaped mobile support, a bus lifting mechanism and an auxiliary vertical calibration mechanism. A U-shaped base plate is arranged at the bottom of the U-shaped mobile support; four moving rollers are arranged under the U-shaped base plate; an L-shaped support is arranged in the middle of the top of the U-shaped mobile support; and the bus lifting mechanism and the auxiliary vertical calibration mechanism are arranged on the L-shaped support. The bus lifting mechanism includes a channel-steel support plate; and three groups of bus lifting units are arranged on the channel-steel support plate. The auxiliary vertical calibration mechanism consists of an L -shaped supporting rod, a stay wire and a hammer. According to the invention, the device having a simple structure can be operated conveniently. With the bus lifting mechanism, the vertical inching lifting of the bus near the support porcelain insulator can be realized smoothly, thereby realizing convenient replacement of the support porcelain insulator. Meanwhile, with the auxiliary vertical calibration mechanism, the perpendicularity of the new support porcelain insulator can be adjusted well and thus the new support porcelain insulator can bear the minimum torque, thereby prolonging the service life.