NOVELTY - Preparing microbial diesel oil comprises manufacturing the microbial oil enriched with unsaturated fatty acid via fermentation culture under a certain culture condition by the high-yield oil microbial strain, taking microbial oil enriched with unsaturated fatty acid as a raw material, separating and purifying many unsaturated fatty acids with good value, and preparing the microbial diesel oil by the residual fatty acid.    USE - The process is useful for preparing microbial diesel oil (claimed).    ADVANTAGE - The process produces the functional fatty acid with good value, which improves the comprehensive economic benefit of the microbial diesel oil and makes the synthetic technique more economic and competent.    DETAILED DESCRIPTION - Preparing microbial diesel oil comprises manufacturing the microbial oil enriched with unsaturated fatty acid via fermentation culture under a certain culture condition by the high-yield oil microbial strain, taking microbial oil enriched with unsaturated fatty acid as a raw material, separating and purifying many unsaturated fatty acids (PUFAs) with good value, and preparing the microbial diesel oil by the residual fatty acid; where it specifically comprises: (a) preparing the microbial grease: after the microbial fermentation and culture, centrifuging and collecting the mycelium of the fermentation liquor; depositing the mycelium according to the proportion of 6 ml per gram of fungus; adding 4 mol/L of hydrochloric acid (HCl), vibrating and uniformly mixing; after placing under at room temperature for 30 minutes, boiling for 3 minutes with boiling water, quickly cooling at -20 degrees C, adding 2 times of volume of extract of chloroform and methanol with ratio of 1:1; after fully vibrating, centrifuging at 5000 rotations/minute for 5 minutes, taking the chloroform layer, adding 0.1% of isopycnic sodium chloride (NaCl) solution, uniformly mixing, centrifuging at 5000 rotations/minute for 5 minutes, taking the chloroform layer, rotating, evaporating and recycling the chloroform to obtain the chloroform; (b) preparing the mixed fatty acid: adding 37% of sodium hydroxide (NaOH)-ethanol solution, placing it into a standard round bottomed flask, returning and saponifying at water of 80 degrees C and obtaining the saponification liquid; after cooling at room temperature, adding water to dissolve the soap completely; adjusting pH to 2-3 by using 10% HCl, adding n-hexane to extract, layering, removing the lower water layer, washing the upper layer to the neutral, adding anhydrous sodium sulfate, reducing pressure, extracting and filtering; rotating, evaporating and recycling the n-hexane to obtain the mixed fatty acid; (c) adopting the urea coating method: adding 95% of ethanol, stirring on a magnetic stirrer, adding the mixed fatty acid to stir uniformly after completely dissolving; mixing the hot reflux for 40 minutes according to the mixed proportion of mixed fatty acid, urea, and ethanol of 1:3.5:10.5; cooling at room temperature, placing for 20 hours in the refrigerator at -5 degrees C, reducing pressure, extracting and filtering; adding n-hexane to the proper filtrate; adjusting pH to 2-3 by using 10% HCl, adding water, fully extracting, separating the organic phase, utilizing the n-hexane to extract the water phase, combining the organic phase, washing to neutral, dewatering by anhydrous sodium sulfate; reducing pressure, extracting and filtering; rotating, evaporating and recycling the organic solvent to obtain the unsaturated fatty acids (PUFAs); and (d) preparing the microbial diesel oil by the residual fatty acid: adding 10-100 g of fatty acid, 2.0-50 g of methanol, and 1.0-3.0 wt.% of concentrated sulfuric acid as the catalyst; controlling the esterification temperature to 60-100 degrees C, reacting for 2-6 hours, reducing the pressure, and distilling and recycling the excessive methanol to obtain the microbial diesel oil; where the inclined plane culture medium that is potato dextrose agar (PDA) comprises 20% of potato leaching agent, 1.8% of agar, and 2.0% of glucose under the natural pH; the initially sieving plate comprises 20% of potato leaching agent, 1.8% of agar, and 2.0% of glucose under the natural pH; the seed culture medium comprises 4.0% of corn starch, 2.0% of glucose, 0.1% of monopotassium phosphate (KH2PO4), 0.01% of magnesium sulfate (MgSO4), 0.1% of yeast extract, and 0.15 of urea, where the pH is 6.4-6.7; and the fermentation production oil culture medium comprises 45-100 g/L of glucose as carbon source, 0.5 g/L of ammonium sulfate ((NH4)2SO4) as nitrogen source, 41.0 g/L of KH2PO4, 41.0 g/L of dipotassium phosphate (K2HPO4), 1.0 g/L of MgSO4, and 2.0 g/L of trisodium citrate, where the pH is 6.0.    DESCRIPTION OF DRAWING(S) - The drawing shows a flow diagram of the process for preparing microbial diesel oil (Drawing includes non-English language text).