NOVELTY - Substrate comprises 5-10 pts. wt. fermented citrus peel, 15-30 pts. wt. purple soil and 0.05-0.8 pts. wt. insecticides. The fermented citrus peel comprises 50-60 mass% of citrus peel dregs and 40-50 mass% of organic materials. The fermented citrus peel is prepared by crushing citrus peel, adding citrus peel with citric acid, carrying out yeast fermentation, adding water and modifiers, mixing the materials, and adding mixed manure, liquid microbial agent and enzyme, mixing and stacking the material, covering the material with straws and carrying out enzymolysis.    USE - The substrate is useful for the growth of citrus seedling (claimed).    ADVANTAGE - The substrate can be simply applied and prepared in a cost effective manner, and rapidly improves the growth rate of citrus seedling.    DETAILED DESCRIPTION - Substrate comprises 5-10 pts. wt. fermented citrus peel, 15-30 pts. wt. purple soil and 0.05-0.8 pts. wt. insecticides. The fermented citrus peel comprises 50-60 mass% of citrus peel dregs and 40-50 mass% of organic materials. The fermented citrus peel is prepared by crushing citrus peel into particle size of 3-5 mm, adding citrus peel with 0.5-1.2% of acid at room temperature, carrying out yeast fermentation for 24-72 hours, turning the mixture for every 12 hours, until pH value of the citrus peel is 6-7, adding water and modifiers, mixing the materials, adjusting the moisture content of the mixed material to 50-60%, adding 50-60% of mixed manure, 0.5% of liquid microbial agent and 0.5-1.5% of enzyme, mixing and stacking the material, covering the material with straws, carrying out enzymolysis at 40-55 degrees C, turning for 1-2 times, adding 1-3% of liquid microbial agents with the fermented mixture and then accumulation, covering with straws, fermenting at 65-70 degrees C, turning for 3-4 times, spreading the obtained material to dry naturally for 2-3 days until the moisture content is less than 30%, pulverizing the mixture and then sieving and screening the material with particle size of 2-5 mm, where the material has nitrogen, Phosphorus and potassium according to the ratio of 2.5-2.8%:0.12-0.16%:0.7-1.3%, adding urea, monoammonium phosphate, potassium ingredients and insect sterilization agent to obtain fermented citrus peel. The organic matter material is obtained from livestock excrement. The modifier is water modifier. The purple soil has pH value of 5-7 and moisture content of less than 30%, and is obtained by crushing and sieving into particle diameter of less than 5 mm. The insecticide is 50% of calcium cyanamide granule. An INDEPENDENT CLAIM is included for use of seedling substrate for the growth of citrus seedling, where the application method comprises spreading the substrate material at thickness of 20-40 cm and covering the substrate with an agricultural plastic film with thickness of 0.004-0.012 mm at room temperature, removing insect eggs for 13 days in summer and 5-7 days in winter, laying the substrate material at thickness of 10-20 cm and then cooling for 1-2 days.