The invention discloses high-concentration full-nutrition functional suspension liquid fertilizer and a preparation method thereof. 1-5 parts of functional additive, 40-60 parts of major element fertilizer, 1-5 of medium element fertilizer, 0.5-2.5 parts of trace element fertilizer, 0.5-2.5 parts of suspension agent and 20-40 parts of water are homogeneously emulsified and evenly mixed in a specific order to prepare the product. The obtained suspension liquid fertilizer is rich in nitrogen, phosphorus, potassium and medium and trace elements and has comprehensive nutrients and a reasonable ratio, and sufficient nutrients can be provided for different stages of plant growth. The functional additive contained in the product has the functions of positively promoting the plant growth and conditioning the soil, the physiological metabolism of plants can be stimulated, the stress resistance can be enhanced, the body immunity can be improved, the soil structure can be improved, the utilization rate of various nutrients by the plants can be increased, the yield of crop products is increased, and the quality of the crop products is improved. The fertilizer is fully water-soluble, good in fluidity and suitable for an integrated irrigation system of water-soluble fertilizer; the fertilizer is produced under normal temperature and normal pressure, the equipment is simple, large-scale production is easily achieved, and the labor degree is reduced.