The invention provides an acidic soil conditioner, a preparation method and application thereof. The acidic soil conditioner is formed by compounding of industrial waste, mineral raw materials and anSE functional material in certain proportion. The SE functional material comprises a glucoamylase treatment substance and amino acid biochar, as well as one or more of alginic acid, polyaspartic acid,polyglutamic acid and potassium fulvate. The acidic soil conditioner provided by the invention can effectively adjust the soil pH value, neutralize free acid, passivate activated aluminum, and solvethe problems of "acidity and toxicity" of soil; being rich in humic acid and organic matters, the acidic soil conditioner can effectively improve soil, restore the granular structure, increase the content of organic matters, and improve the water retention, fertility increasing and breathability of soil; the acidic soil conditioner can improve the rhizosphere soil microenvironment, enhance root activity, and promote nutrient uptake and utilization, also can improve the crop stress resistance and effectively prevent crop premature senescence, thus being a conditioner having the efficacy of improving soil and promoting crop growth.