NOVELTY - A microbial grease with agricultural waste sweet potato vine as raw material is prepared by (A) preparing sweet potato vine hydrolysis liquid, (B) preparing liquid deep fermentation culture medium, (C) preparing oil bacteria fermentation seed, (D) fermenting and producing microbial grease, and (E) ultrasonic extracting of microbial grease. The step (E) comprises mixing grease bacterium with hydrochloric acid, boiling, and adding extracting liquid formed by mixing chloroform with methanol; and ultrasonically extracting remaining solid-liquid mixture with same volume of chloroform.    USE - Method for preparing microbial grease with agricultural waste sweet potato vine as raw material (claimed).    ADVANTAGE - The method converts waste material into useful product. The obtained hydrolysate has rich nutrition.    DETAILED DESCRIPTION - Microbial grease with agricultural waste sweet potato vine as raw material is prepared by (A) preparing sweet potato vine hydrolysis liquid, (B) preparing liquid deep fermentation culture medium, (C) preparing oil bacteria fermentation seed, (D) fermenting and producing microbial grease, and (E) ultrasonic extracting of microbial grease. The step (A) comprises based on volume ratio of 1:5-10 (g/ml), mixing crushed or shred sweet potato vine with citric acid buffer liquid (0.05 mol/L), where pH of 4.8, sterilizing solid-liquid mixture at 115 degrees C for 20 minutes, adding 15 international units (IU) cellulose and 100 IU of pectinase to per gram of solid-liquid mixture, preparing enzyme mixture, vibrating enzyme mixture at 50 degrees C for 4 days, after solid-liquid separating, obtaining sweet potato vine hydrolysis liquid. The step (B) comprises regulating pH of sweet potato vine hydrolysis liquid at 5.5, sterilizing at 115 degrees C for 20 minutes, obtaining liquid deep fermentation culture medium, or, according to mass-volume ratio of 3-6: 100 (g/ml), adding sugar into hydrolysis liquid, regulating pH of hydrolysis liquid containing sugar as 5.5, sterilizing at 115 degrees C for 20 minutes, and obtaining liquid deep fermentation culture medium. The step (C) comprises activating oil bacteria seed preserved at low temperature by yeast extract peptone dextrose (YPD) liquid culture medium, inoculating to another YPD liquid culture medium, culturing to exponential phase, and obtaining oil bacteria fermentation seed. The step (D) comprises mixing oil bacteria fermentation seed with liquid deep fermentation culture medium based on volume ratio of 5%, venting and vibrating to culture for 8-12 days, with speed of 180-200 revolutions/minute (rpm), obtaining fermented product, after solid-liquid separation, collecting solid, and preparing oil strain. The step (E) comprises:    (A) according to mass-volume ratio of 1:4 (g/ml), mixing grease bacterium with hydrochloric acid (2 mol/L), boiling for 10 minutes, and adding extracting liquid formed by mixing chloroform with methanol at volume ratio of 2:1;    (B) preparing mixed solution, ultrasonically extracting mixed solution for 30 minutes, and standing or centrifuging and layering;    (C) collecting organic phase, ultrasonically extracting remaining solid-liquid mixture with same volume of chloroform; and    (D) standing or centrifuging and layering, collecting organic phase, after chloroform ultrasonic extraction for 2-3 times, mixing all of lower-layer organic phases, distilling and recycling organic solvent, and remaining transparent and clear liquid component as microbial grease.