The invention discloses an organic substrate for raising rice seedlings. The substrate is prepared from powders of livestock and poultry manure subjected to harmless treatment, waste powders after plant straw and fruit processing, humic acid, metalaxyl, fludioxonil, azoxystrobin, trace elements, complexing agents, enhancers, drought-resistant agents, nitrogenous fertilizers, phosphate fertilizers,potash fertilizers, long-acting organic PH regulating agents, fillers and additives. The organic substrate, by adopting the leftovers after crop straw and fruit processing, the powders of livestock and poultry manure subjected to harmless treatment and microbial strains as the main raw materials, does not need peat and plough layer soil, thereby reducing the utilization of non-renewable resourcesand the damage to farmland soil. The organic substrate for raising the rice seedlings has good packing, reduces the incidence of blight, bakanae disease and cotton rot, promotes fast green return, more tillering and early maturation of rice, and can increase the yield and the rice output rate.