NOVELTY - A high precision non-aqueous nano diamond grinding liquid contains (in wt.%) nano diamond grains (0.1-10), diffusion stabilizer (0.1-10), suspending agent (0.1-20) and remaining diffusion medium. The grinding liquid has granularity of 130 nm or less. The ratio of D10 to D50 is 50% or more and the ratio of D90 to D50 is 200% or more. The diffusion agent is sodium tripolyphosphate, sodium silicate, cetyl sodium sulfate, polystyrene sulfonic acid, hydroquinone, phenylenediamine, dodecylamine or octadecylamine.    USE - High-precision non-aqueous nano diamond grinding liquid used for precision grinding and polishing of high precision target materials, rigid alloy, light disc mold, computer magnetic head, computer hard disk, solar cell panel, deliquescent crystal and special optical glass (all claimed).    ADVANTAGE - The non-aqueous nano diamond grinding liquid has high polishing efficiency, polishing quality, and effectively eliminates deliquescence, hydrolyzation, chemical erosion and electrochemical erosion.    DETAILED DESCRIPTION - A high precision non-aqueous nano diamond grinding liquid contains (in wt.%) nano diamond grains (0.1-10), diffusion stabilizer (0.1-10), suspending agent (0.1-20) and remaining diffusion medium. The grinding liquid has granularity of 130 nm or less. The ratio of D10 to D50 is 50% or more and the ratio of D90 to D50 is 200% or more. The diffusion agent is sodium tripolyphosphate, sodium silicate, cetyl sodium sulfate, polystyrene sulfonic acid, hydroquinone, phenylenediamine, dodecylamine, octadecylamine, stearyl trimethylamine, distearyl dimethylammonium chloride, benzoic acid, oleic acid, tannin, salicylic acid, dodecoic acid, octadecenoic acid, meta-titanic acid ester coupler, tin-like coupler and/or silane propyl coupler. The suspension agent is ethyl alcohol, ethylene glycol, isopropyl alcohol, glycerol, laurinol, polyethylene glycol, polyacrylic acid, polymethacrylic acid, polyethyleneimine, polydiene allyl dimethyl ammonium chloride, N-cymene ethylene chloropyridine polymer, methyl aniline polymer, hydroxymethyl cellulose and/or polyoxyethylene ether. The diffusion medium is acetone, ethanol, ethylene glycol, dimethyl sulfoxide, acetic acid, cyclohexane, petroleum ether and/or 9-45C mineral oil. An INDEPENDENT CLAIM is included for method for preparing high-precision non-aqueous nano diamond grinding liquid, which involves adopting air flow crushing, colloid grinding or ball grinding, refining the diamond raw material till the grain diameter of the diamond raw material with 60% metal content is less than 200 nm, decorating the outline of diamond by high temperature hot processing or reformation ball grinder, circularly processing for 0.5-48 hours by transferring the diamond raw material into the gas state flow fluidized bed, processing at 200-1000 degrees C and at flow rate of 100-500 L/hour using gas comprising oxygen, ozone, helium, argon gas, nitrogen, fluorine and/or methane, mechanically purifying so as to deeply purify the diamond raw material through overflow washing or ion exchange resin using acid chosen from hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, hydrofluoric acid, perchloric acid and/or boric acid, alkali processing the diamond raw material using potassium hydroxide and/or sodium hydroxide, eliminating impurities by using upward water flow, separating the diamond grains, and eliminating the rough grains and fine grains using solvent chosen from deionized water, acetone, alcohol, isopropanol, butyl alcohol, glycol, glycerol, dimethyl sulfoxide, N,N-dimethylformamide, N-methyl pyrrolidone, cyclohexane, petroleum ether and 9-45C mineral oil, mixing the separated diamond, diffusion medium, diffusion stabilizer and suspending agent, stirring or ultrasonically and uniformly scattering, and adding the pH adjusting agent, antistatic agent and antioxidant in order.