The invention relates to a special liquid package cotton fertilizer for improving soil, and a preparation method and application method of the liquid package fertilizer. According to the special liquid package cotton fertilizer for improving soil, the special liquid package fertilizer consists of a composite microbial liquid fertilizer and a macroelement water-soluble fertilizer, wherein the composite microbial liquid fertilizer consists of an amino acid fermentation liquid, fulvic acid, microbial bacteria, a nitration inhibitor and polyaspartic acid, and the macroelement water-soluble fertilizer consists of urea, monoammonium phosphate, potassium chloride, magnesium sulfate heptahydrate, EDDHA-iron, EDDHA-zinc, EDDHA-manganese, EDDHA-copper, boric acid, carboxymethyl cellulose, an amino acid fermentation liquid, bentonite and sodium pyrophosphate. The invention also discloses the preparation method and application method of the package fertilizer. According to the special liquid package cotton fertilizer for improving the soil provide by the invention, the requirements on nutrients in different growth and development periods of cotton can be met, and salinization of soil in Xinjiang can be improved. The application method of the special liquid package fertilizer conforms to the growth characteristics and fertilizer requirement laws of the cotton.