In order to provide scientific basis for the utilization of cassava alcohol fermentation mash and the high-yield and high-efficiency cultivation of cassava, compound microbial inoculum was inoculated into the cassava alcohol fermentation mash to prepare bacterial manure, which was then applied to two cassava varieties, Nanzhi 199 and SC 205 to explore the optimum application amount, application method and application concentration. The results showed that when the inoculation amount of the compound microbial inoculum was 2‰ of the mass of the mash, the requirements of industrial production of liquid bacterial manure and agricultural application can be met, saving costs. After the emergence of cassava seedlings, if they were drenched with the bacterial manure of cassava alcohol fermentation mash through roots once according to the amount of 67.5 t/ha and irrigated with the bacterial manure once every 15 d under drought conditions, both the yield and quality of cassava can be improved significantly. The yield and starch content of Nanzhi 199 reached 26 196.23 kg/ha and 30.32%, 36.57% and 4.75 percentage points higher than those of CK. The yield and starch content of SC 205 reached 41 126.06 and 23.74%, 99.25% and 3.19 percentage points higher than those of CK. Under the application modes of foliar spray, root irrigation and foliar spray + root irrigation, the fertilization effect was more obvious. When undiluted bacterial manure of cassava alcohol fermentation mash was applied according to the amount of 52.5 t/(ha·time), the fertilization effect of the application mode of foliar spray + root irrigation was the best. The bacterial manure from cassava alcohol fermentation mash can be directly applied without dilution, and the fertilizer efficiency will be reduced significantly after dilution.