The invention discloses a grapefruit planting soil formulation. The grapefruit planting soil formulation is composed of, by weight, 30%-40% of vegetable garden soil, 10%-20% of leaf mould, 10%-20% of river sand, 10%-20% of mountain clay, 6%-10% of saw dust, 4%-6% of bone meal, 4%-6% of cow dung organic fertilizer and 1%-3% of soybean meal. A preparation method includes: grinding soybeans in a grinder to obtain the soybean meal; adding fresh cow dung into a fermentation tank, and fermenting for 7-8 days to obtain the cow dung organic fertilizer; soaking bones in water, cleaning the bones, adding the bones into a drying oven, taking out the bones, and using the grinder for grinding the bones to obtain the bone meal; adding the vegetable garden soil, the leaf mould, the river sand, the mountain clay, the saw dust, the bone meal, the cow dung organic fertilizer and the soybean meal into planting pots, and well mixing for planting grapefruits. The grapefruit planting soil formulation has the advantages of excellent grapefruit growth effects and the like.