The invention relates to a production device and a production method of a biomass organic carbon-based potash fertilizer. The production device comprises a placement tank, pretreatment equipment, a pelletizer, a dryer, a packing machine and a control system, wherein a feeding conveyer is arranged between the placement tank and the pretreatment equipment; the pretreatment equipment comprises a stirring mixer, a screening machine and a pulverizer; the control unit comprises a control panel, a programmable controller and a metering unit; the control unit controls starting and stopping of the pretreatment equipment, the pelletizer, the dryer and the packing machine. By adopting the production device and the production technology, the required biomass organic carbon-based potash fertilizer is finally obtained in manners of screening, stirring and mixing by the pelletizer and the dryer. The fertilizer is not only healthful and clean, but also small in pollution on environment, high in production efficiency, high in automatic degree, convenient to control, and economical in cost; the produced fertilizer mainly contains a carbon element, which can be decomposed in soil, is free of residue absolutely, and has long-acting characteristics of improving the soil.