The invention discloses a fermented cake fertilizer, its preparation method and application. The invention overcomes the defects of the prior art and provides a fermented cake fertilizer which is suitable for tobacco growth. The fermented cake fertilizer is characterized in that a bean cake is subject to microbial strain fermentation, then macro-molecular compounds in the cake fertilizer are converted into micro-molecular compounds, nitrogen in protein is converted into amino acid to release nitrogen in the cake fertilizer in advance, thus the releasing rule of nitrogen is consistent with the nitrogen absorption rule of tobacco; and microbes generate protease in the process of growth, fermented materials are put in water, protease converts protein in the bean cake into amino acid or micro-molecular nitrogen containing compounds, plants can directly adsorb amino acid, or the micro-molecular nitrogen containing compounds are easy to be converted into absorbable nitrogen of plants in soil. According to the invention, the purpose of improving the tobacco quality can be achieved, and simultaneously the effects of increasing soil biological activity, improving soil structure, and raising soil fertility are achieved.