The invention discloses a carbon-based compound fertilizer with a high potassium utilization rate. The preparation method comprises the following steps: according to nutrient requirements of flue-cured tobacco, preparing a base fertilizer according to a scientific and reasonable proportioning method; preparing a carbon-based compound fertilizer according to a ratio 7:3 of the base fertilizer to biomass charcoal, mixing into an organic adhesive prepared from 2.5% of sodium alga acid, chitosan or wood vinegar, fully and uniformly mixing, and taking out the mixture; preparing spherical particles with the particle size of less than 6mm from the mixture by using a granulator, and drying at a low temperature, thereby obtaining the carbon-based compound fertilizer. The carbon-based compound fertilizer disclosed by the invention has the advantages that (1) the nutrition is comprehensive and rich, one-time topdressing is performed in the uncovered ridging period during flue-cured tobacco cultivation, the operation is convenient, and the yield and output value of the flue-cured tobacco and the ratio between medium and high-grade tobacco leaves can be obviously improved; (2) the release rate of potassium in the fertilizer in soil is retarded, the effectiveness of the potassium is improved, and the potassium content in the tobacco leaves, potassium accumulation in the flue-cured tobacco and the potassium utilization rate in the flue-cured tobacco fertilizer are obviously improved; and (3) the carbon-based compound fertilizer is readily available in raw materials, environment-friendly and safe.