NOVELTY - A rice seedling substrate comprises 100 pts. wt. rice seedling culture matrix and 5 pts. wt. seedling strengthening agent. The rice seedling culture matrix comprises black soil, organic mixed material and 2.5% fenaminosulf. The organic mixed material comprises crushed rape seed stalk or straw, mulberry branch or cotton straw, mushroom culture waste, straw rotten agent, carbamide, and nitrogen-phosphorus-potassium compound fertilizer. The seedling strengthening agent comprises plant growth retardant, acid-binding agent, phosphate fertilizer, and ammonium persulfate.    USE - Rice seedling substrate.    ADVANTAGE - The rice seedling substrate is green and environment-friendly, can reduce labor cost and improve seedling quality. The seedling has high survival rate and high yield after breeding for 20 days.    DETAILED DESCRIPTION - A rice seedling substrate comprises 100 pts. wt. rice seedling culture matrix and 5 pts. wt. seedling strengthening agent. The rice seedling culture matrix comprises black soil, organic mixed material and 2.5% fenaminosulf at weight ratio of 300:700:0.05. The organic mixed material comprises crushed rape seed stalk or straw, mulberry branch or cotton straw, mushroom culture waste, straw rotten agent, carbamide, and nitrogen-phosphorus-potassium compound fertilizer at weight ratio of 300:200:200:4:5:5. The seedling strengthening agent comprises plant growth retardant, acid-binding agent, phosphate fertilizer, and ammonium persulfate at weight ratio of 100:100:200:600. The plant growth retardant comprises 10% paclobutrazol, zinc sulfate, phosphate fertilizer, potash fertilizer, and coal ash powder at weight ratio of 1:2.5:40:30:30. The acid-binding agent comprises industrial sulfuric acid and potassium fertilizer at weight ratio of 60:12-13:30. An INDEPENDENT CLAIM is included for production of the rice seedling substrate, comprising mixing rice seedling culture matrix components, drying, crushing, sieving, uniformly stirring for 10 minutes, then stacking, covering with plastic film, preserving heat, and fermenting for 2 months, adding seedling strengthening agent into the fermentation product and stirring for 15 minutes to obtain the rice seedling substrate.