The invention discloses a cooling and drying device for biomass briquette fuel and a method thereof, and belongs to the field of energy technicalization. The cooling and drying device comprises a box body and a material conveyor arranged below the box body. Holes are formed in a conveyer belt of the material conveyor. An input opening and an output opening are formed in the two ends of the box body. The box body is separated into at least two cooling and drying chambers through partition plates. The upper portions of the cooling and drying chambers are communicated through an air exhausting pipe and an induced draft fan. The method comprises the steps that 1, the fuel is conveyed into a first cooling and drying chamber through the material conveyor, drying air enters the first cooling and drying chamber from the lower portion of a fuel bed, and after the drying air penetrates through the fuel bed, the drying air is exhausted out through the upper portion of the fuel bed; and 2, the primary cooled fuel is conveyed into a second cooling and drying chamber, fuel of which the temperature is close to the room temperature is obtained, and finally the fuel is packed. According to the cooling and drying device for the biomass briquette fuel, the structure is simple and practical; relative movement between the fuel is avoided in the conveying process of the fuel, and thus the broken rate of the fuel is reduced; the drying rate of the fuel can be adjusted according to the actual operational needs, so that energy consumption is reduced; the device is especially suitable for lower-density biomass briquette fuel with the diameter being greater than 20 mm.