A multi-grade firewood burning stove is composed of a firewood burning chamber (3), a firewood inlet (2) and a stove fence (1) at the front part of the chamber, and air guiding ports (4) at the rear part of the chamber. The firewood burning chamber (3) and a 2-3 grade gas combustion chamber (5) at the rear are arranged in a line on the ground and are connected through their own air guiding port. An inner top wall (8) of each chamber (3, 5) is crossly arched. A dust outlet (6) is arranged at the lower part of the gas combustion chamber (5); an air suction device (7) is at the rear side of the last grade gas combustion chamber. The stove is used to dry granules like grains and saw dust. The fuel thereof is the remaining materials after processing bamboos and woods or other combustible refuse. The invention uses wastes and protects environment. Stove gas is generated while burnt firewood generates heat; then the stove gas is burnt in grade; and heat is stored in each chamber. The combustion is full; heat yield is high and heat supply is uniform and long lasting.