The invention discloses a barrel driving mechanism of a heavy concrete mixer truck. The barrel driving mechanism of the heavy concrete mixer truck comprises a frame and a barrel, wherein the barrel is used for storing concrete and is arranged on the upper side of the frame; one end of the barrel is closed, and an opening is formed in the other end of the barrel; the closed end of the barrel is hinged to the frame through a bearing seat; the opening end of the barrel is supported on the frame through a supporting wheel mechanism; a roller way and a gear ring are arranged in the middle of the barrel; an auxiliary supporting wheel matched with the roller way and a gear matched with the gear ring are arranged on the frame and are elastically supported on the frame through a support; the gear is connected with a power device; the power device drives the gear; the gear drives the barrel to rotate. The two ends of the barrel are mounted on the frame through the bearing seat and the supporting wheel mechanism respectively, the auxiliary supporting wheel and the gear are arranged in the middle of the barrel to drive the barrel, the structure and the stress are reasonable, and the gear only achieves a driving effect, so that the service life is prolonged.