The invention discloses a tunnel furnace unit structure, which comprises an upper unit and a lower unit, wherein stand bars are arranged under the lower unit, the top of the upper unit is provided with upper unit heaters and motors, the side of the lower unit is provided with a fan, the top of the upper unit is provided with upper unit cabling grooves which comprise a side cabling groove I, a side cabling groove II and a bottom cabling groove which are arranged respectively on the three sides of the four upper unit heaters, the side of the lower unit is provided with two lower unit cabling grooves which are respectively in a hollow pipe shape, the two lower unit cabling grooves are correspondingly arranged on positions extending downwards vertically of the bottom cabling groove, the stand bars are provided with a bus box internally provided with a relay and a tunnel furnace control device, and the bus box is provided with a through hole in the upper surface. According to the tunnel furnace unit structure, the unit structure of the tunnel furnace is simple, a line is neat, the line is guaranteed to be arranged outside the tunnel furnace, and the cabling position does not influence the normal use of the tunnel furnace.