The idler type steel tube annealing furnace mainly includes feeding frame, heating furnace body, cooling water tank and discharging frame. A number of continuously rotating idlers are respectively arranged in the feeding frame, the heating furnace body, the cooling water tank and the discharging frame. The reducer drives the idlers to rotate continuously through the chain drive, so that the workpiece on the idlers can move forward continuously, and the frequency conversion speed regulation is stable and reliable. In this way, there is no fixed contact point between the workpiece and the roller shaft, the workpiece is heated evenly, without damage, and the deformation is small. At the same time, because the idler in the annealing furnace is always rotating in the heating furnace, the heat loss is relatively small, and the heat efficiency in the furnace is high. A number of debris removal ports are designed under the furnace to keep the furnace clean and improve product quality.