NOVELTY - Prepared high-purity silicon nano-dimensional porous structure using rice husk, comprises (i) pre-treating rice husks; (ii) extracting high purity nano-silica from rice husk ash; and (iii) carrying out thermal reduction of silica under argon gas atmosphere, adding magnesium powder and nano-silica, mixing by adding materials into furnace, reacting, and washing, purifying by adding 2-10% hydrochloric acid solution having pH of 7, filtering to obtain a filtrate and filter cake, where the filtrate can be used in medicine and agriculture, or carrying out crystallization treatment.    USE - The high-purity silicon nano-dimensional porous structure is useful in medicine, and agriculture fields (claimed).    ADVANTAGE - The method can provide heat for subsequent thermal reaction; reduces energy consumption, and greenhouse gas emissions; produces high purity magnesium chloride byproducts, and metallic magnesium prepared by electrolysis; and is environmental friendly.    DETAILED DESCRIPTION - Prepared high-purity silicon nano-dimensional porous structure using rice husk, comprises (i) pre-treating rice husks by washing rice husks using 1-10% hydrochloric acid, boiling rice husk, where the mass ratio of hydrochloric acid solution and rice husk is 5-40:1, and the boiling time is 0.5-2.5 hours, pickling rice husk by adding water, and drying, feeding dried rice into a combustion furnace, marinating combustion temperature at 650-900 degrees C, burning for 20-120 minutes, to obtain rice husk ash; (ii) extracting high purity nano-silica from rice husk ash by adding rice husk ash with 10-25 wt.% sodium carbonate aqueous solution into a reactor, in a solid-liquid mass ratio of 1:5-10, heating at 100-150 degrees C, carrying out enzymatic hydrolysis for 0.5-3 hours, and filtering off carbon residue, to obtain filtrate-containing silica material, reducing the filtrate temperature to 80-60 degrees C, passing through purified exhaust gas, reacting for 1-4 hours, precipitating, and filtering, returning the filtrate, recycling the filter cake, washing with water, and drying, to obtain nano-silica, and washing wastewater returned to boiling step, recycling, and drying under heat, and carrying out combustion in presence of exhaust gas heat; and (iii) carrying out thermal reduction of silica under argon gas atmosphere, adding magnesium powder and nano-silica in a mass ratio of 0.8-1.2:1, uniformly mixing by adding the materials into the furnace, reacting at 750-850 degrees C for 2-4 hours, and washing, purifying by adding 2-10% hydrochloric acid solution having pH of 7, filtering to obtain a filtrate and filter cake, where the filtrate, or carrying out crystallization treatment of chloride crystals obtained, and magnesium metal obtained, and washing the filter cake with water, drying to obtain the final product, where the heat source used while drying is combustion exhaust gas heat.