The invention discloses a compound liquid fertilizer with high suspension degree, and a preparation method and an application thereof, and belongs to the liquid fertilizer industry field. The preparation method comprises the steps: adding macromolecule organic sugar into a clay material to be used as a basal suspending agent I, and carrying out first suspension chelation of a major element and a trace element at the temperature of 40-60 DEG C; followed by controlling the temperature at 20-30 DEG C, slowly adding a plant growth regulator and a surface active material, fully mixing uniformly, finally adding macromolecule cellulose and an analog thereof as a suspending agent II, carrying out second suspension chelation, and fully stirring to obtain the compound liquid fertilizer with high suspension degree. The prepared compound liquid fertilizer with high suspension degree has comprehensive nutrients, high content, low cost, good liquidity, good stability and good dissolvability, and is beneficial for crops to efficiently absorb and utilize. The preparation method is simple in process and easy to implement. The compound liquid fertilizer is an ideal fertilizer source for water and fertilizer integration for drip irrigation, sprinkler irrigation, water flushing and the like.