The invention discloses a manufacturing method of a non-ground stereo greening organic composite substrate, and belongs to the technical field of gardening. The substrate is composed of the following components in parts by weight: 2 to 3 parts of peat, 2 to 3 parts of husk coal slag, 3 to 5 parts of potato residues and agricultural waste mixed material fermented particles, 1 to 2 parts of coco coir silk, and a little amount of composite fertilizer, which is added to increase the nutrients. The manufacturing method comprises the following steps: drying agricultural wastes in the sun, grinding agricultural wastes into silks with a diameter not more than 2 mm and a length not more than 25 mm or particles with a particle size not more than 5 mm; then mixing the processed agricultural wastes with potato residues, adding a high temperature aging inoculant containing beneficial microbes, carrying out composting, aging, and fermentation so as to obtain particles of potato residues and agricultural waste mixed material; preparing bio-synthesized peat and husk coal slag; then adding coco coir silk and composite fertilizer, fully stirring and evenly mixing the raw materials and auxiliary materials together, loading the mixture into bags, weighing the bags, and storing the bags in a warehouse. The produced organic composite substrate has the advantages of fluffy texture, light weight, and rich nutrients, and is very suitable for the non-ground stereo greening such as arterial street guard bars, skyways, and the like.