The invention discloses a flue device of a firewood stove. The flue device comprises a firewood stove body and a flue body, wherein the left side of the flue body is arranged at the lower end at one side of the firewood stove body; the middle part of the flue body is positioned below ground; the right side of the flue body extends to the outside of a wall; a first ash cleaning hole is formed in the middle of the flue body; a second ash cleaning hole is formed in the bottom end at the right side of the flue body; the first ash cleaning hole communicates with the ground through a pipeline; the right side part of the flue body is arranged along the wall; a protective net is arranged on a position, on an indoor section, of the right side part of the flue body; and a filter screen is arranged inside an outlet in the right side part of the flue body. The flue device of the firewood stove provided by the invention does not occupy an indoor space, achieves effective utilization of heat, and is energy-saving and environmentally friendly.