A biomass pellet furnace for coating and heating, characterized in that it includes a cold air inlet, a heating inner tube, an air filter, a negative pressure initiating device, a deflector, a hot air outlet, a spiral coil, and a heated inner cavity. The heating inner tube is provided with an upper part of the re-granulation furnace, and the outside of the heating inner tube shown is provided with an air filter. The air filter is provided with a cold air inlet and a hot air inlet. A negative pressure initiation device is provided in the space between the two, the deflector is disposed below the heating inner tube, the spiral judge is disposed in the heated inner cavity, and the surface of the spiral coil is flat. The tubes are in close contact.