The present invention relates to a seedling substrate for solanaceous vegetables and a producing method therefor. The seedling substrate comprises a mixture obtained by mixing a main material, vermiculite and perlite in a volume ratio of 3-4 : 0.6-0.7 : 0.3-0.4, and is obtained by adding 10 g to 15 g of paclobutrazol and 1.5 kg to 2 kg of 0.4 mol/L to 0.5 mol/L dilute sulfuric acid solution per cubic meter of mixture, and fully mixing same until uniform. Said main material is obtained by adjusting a cow bedding removed material to a carbon/nitrogen ratio of 25-30:1, a pH value of 6.5-7.0, and a water content of 60%-65%, then introducing EM fermentation bacteria, stacking, covering a film, and performing high temperature aerobic fermentation and air drying. By using the substrate to grow seedlings, the root systems are well developed and will not grow wildly, the seedlings are strong, damping-off and root rot are significantly reduced, and the damage caused by aphids are reduced; virus diseases during the seed
