The invention discloses nutrient soil used for planting of ornamental tree seedlings. The nutrient soil is prepared by the following steps of S1, pretreatment S2, composting fermentation, S3, decomposing; S4, detection and S5, granulation, wherein, in the step S1, municipal domestic sludge is crushed, and the crushed municipal domestic sludge passes through a 300-500 mesh screen to remove large granules in the domestic sludge; in the step S2, deodorized sludge is dewatered to a first water content ratio, active microorganisms are added into the dewatered deodorized sludge, straw and biologicalcarbon are put into the dewatered deodorized sludge, and temperature is controlled to be first temperature and fermentation is performed for second time; in the step S3, fermented sludge prepared inthe step S2 is dewatered to a second water content ratio; in the step S4, the content of phosphorus, acid and potassium and the content of organic matter in nutrient soil are detected, and the nutrient soil is adjusted by adding lots of elements including the phosphorus, the acid, the potassium and the like; and in the step S5, the adjusted nutrient soil is put into a granulator and is made into granules. The nutrient content of the prepared nutrient soil is 2-3 times more than that of common soil; the nutrient soil is green and environment-friendly; and when the nutrient soil is used for agriculture and forestry production, production efficiency can be greatly increased, and the economic income is increased.