The invention provides a shaddock orchard soil improvement agent and a preparation method thereof. The shaddock orchard soil improvement agent is prepared from, by weight, 18-39 parts of organic fertilizers, 5-12 parts of peat soil, 1-5 parts of montmorillonite, 1-5 parts of zeolite, 2-6 parts of sepiolite, 4-8 parts of calcium magnesium phosphate fertilizers, 1-3 parts of bacillus licheniformis, 1-3 parts of azotobacter chroococcum and 1-3 parts of actinobacillus capsulatus. Compared with the prior art, the shaddock orchard soil improvement agent which is prepared from the organic fertilizers, the peat soil, the montmorillonite, the zeolite, the sepiolite, the calcium magnesium phosphate fertilizers, the bacillus licheniformis, the azotobacter chroococcum and the actinobacillus capsulatus has advantages that improvement of shaddock orchard soil, supply of trace elements, improvement of soil physical structure and improvement of soil fertility are realized, and accordingly shaddock yield is increased.