The invention discloses a body mechanism of a column type oil tank spraying robot. The body mechanism comprises a working arm portion, a lifting mechanism portion and a column mechanism portion. The working arm portion comprises a left working arm and a right working arm which are identical in structure and symmetrical in position, and each working arm is provided with an over-arm trolley traveling mechanism and an under-arm trolley traveling mechanism. The lifting mechanism portion comprises an upper steel cable and a lower steel cable, wherein two ends of the upper steel cable are connected with the left side and the right side of a waist rotating portion respectively, one end of the lower steel cable is connected with a column base plate, and the other end of the lower steel cable is wound on a reel of a winch. A connecting disc capable of moving vertically is arranged in the middle of a column, the column and a vent hole of an oil tank are connected through the disc, and a tank bottom fixing portion of the column is fixed at the tank bottom through magnetic attraction. According to the body mechanism of the column type oil tank spraying robot, the two working arms can be driven to lift stably and flexibly, the occupied area is small, the fixing mode is reliable, installation and dismounting are convenient, and the body mechanism is applicable to a plurality of kinds of tanks.