The invention discloses a manioc waste residue drying device and a device for manufacturing a firewood bar and charcoal. The drying device comprises a throw-fly-type pre-drying section, a preceding stage gas-solid separation drying section and a backward stage gas-material mixed hot air drying section which are connected sequentially; the preceding stage gas-solid separation drying section comprises a drying device with a sandwiched layer, materials are delivered in an inner cavity of the drying device, and hot air is introduced in the sandwiched layer; material outlets of the preceding stage gas-solid separation drying section and the backward stage gas-material mixed hot air drying section are respectively connected with a cyclone separator; and the exhaust port of each cyclone separator is also connected with a dehumidifying fan. By adopting the drying device, the manioc wet waste residue which is generated in the manioc starch production process and has the moisture content still as high as 70% after mechanical dehydration can be dried once into dry waste residue with the moisture content less than or equal to 15%; and the firewood bar which is obtained by the compression of the dry waste residue and the charcoal products which are formed by further burning have the advantages of low ash content, low sulphur content, high volatile constituent, high heat and the like, and are superior biomass energy sources.