The invention discloses a novel and efficient multi-necking graded cyclone coal powder combustion machine. The novel and efficient multi-necking graded cyclone coal powder combustion machine comprisesan inner combustion cavity and an outer cyclone air channel which are sequentially coaxially arranged from inside to outside. The outer cyclone air channel communicates with a secondary air pipeline.A fire-proof layer is arranged on the inner wall of the inner combustion cavity. In the cavity, the inner combustion cavity is divided into a primary combustion chamber and a secondary combustion chamber by a secondary necking and a primary necking which are annularly arranged from the bottom to top. A plurality of layers of annularly arranged ventilation channels are arranged on the cavity wallof the inner combustion cavity of the primary combustion chamber and the second combustion chamber. The ventilation channels connect the outer cyclone air channel with the inner combustion cavity, andthe axes of the ventilation channels are inclined to the wall face tangent of the inner combustion cavity. A coal spraying pipe is directly connected to the primary combustion chamber. The spurt androtational flow effects of combustion assisting air are improved by the special necking and internal and external layered structure, and therefore the flow field distribution is changed, and the coalpowder discrete degree is reinforced. The combustion range is controlled to reduce the temperature of the inner wall of the inner combustion cavity. Coal powder combustion efficiency is improved, andthe combustion problem of large amount of coal is solved.