The invention discloses vegetable substrate nutritional soil and a preparing method thereof. The vegetable substrate nutritional soil is prepared from corn straws, soybean curd residues, edible mushroom waste, chicken manure, river sand, river sludge, coal residues, pig bones, urea, wood shavings, pig manure, diatomite, traditional Chinese medicine residues, peanut shells, wheat straws, soybean straws, a microbial fermentation agent and agar liquid by the following steps: putting the microbial fermentation agent into the agar liquid to cultivate; putting the chicken manure and the pig manure into the edible mushroom waste to perform fermentation cultivation; grinding and mixing the corn straws, the coal residues, the pig bones, the wood shavings, the diatomite, the peanut shells, the wheat straws and the soybean straws; mixing the soybean curd residues, the river sand, the river sludge and the traditional Chinese medicine residues; adding the microbial fermentation agent and performing fermentation; adding other raw materials and performing fermentation again. The raw materials are obtained locally and cheap, have low cost and high buffer capability, avoid contradiction between water, nutrient and supplied oxygen, can be repeatedly recycled, and avoid environmental pollution residues.