The invention discloses a vegetable seedling growing substrate, and belongs to the technical field of soilless culture techniques. The substrate comprises the following components: coconut shell base stock, alcohol biogas residue, carbonized rice hull, biogas slurry, perlite and vermiculite at a ratio of (15-30):(15-30):(15-25):(0.5-2):(5-10):(15-25), wherein the water content of the substrate is 35-50%, the total porosity is 65-95%, the organic substance content is greater than or equal to 20%, the total nutrient content is 3-5%, the particle size is 0.1-4.9 mm, the volume-weight is 0.2-0.8 g / cm<3>, the gas water ratio is 1:(2-4), the EC value is less than or equal to 2.5 mS / cm, and the pH value is 5.8-7.5. The vegetable seedling growing substrate mainly adopts organic waste as raw materials which are subjected to high-temperature fermentation treatment, the waste is turned into wealth, and the harm is turned into goodness, and moreover, the substrate is low in cost, light in weight, comprehensive in nutrient, is applicable to growth and development of vegetable seedlings, and is a good substrate for vegetable soilless culture industrial plug seedling.