The invention discloses a preparation method of a roasted potato spice. The preparation method comprises the following steps: cleaning and peeling, crushing and pulping, pressure-reduced filtration, yeast fermentation, high-temperature baking, homogeneous emulsification and the like, i.e., the method comprises the following steps: performing cleaning and peeling, crushing and pulping, pressure-reduced filtration and yeast fermentation treatment on potatoes, performing high-temperature baking at 60-350 DEG C, and then performing homogeneous emulsification by virtue of a colloid grinder. The prepared roasted potato spice disclosed by the invention is uniformly sprayed on cut tobaccos in a cigarette feeding process, and the 'baking fragrance' notes of the cigarettes can be showed, so that the smoking quality and sensory comfort level of the cigarettes can be improved, the aroma of the cigarettes can be significantly increased, the aftertaste can be improved, and the irritation and miscellaneous odors also can be relatively greatly reduced. The product disclosed by the invention is low in cost, simple in process and high in safety, and is worthy of popularization and application in the whole industry.