Method for preparing biodiesel from biolipid

The invention discloses a method for preparing biodiesel from biolipid and relates to the field of renewable new energy sources. The method comprises the three steps of (1) preprocessing the raw material biolipid; (2) carrying out an ester exchange reaction under the conditions that the mol ratio of the standard raw material lipid to dimethyl carbonate is 1: (3-9), the dosage of a solid alkali catalyst is 0.01-0.2% of the mass of the standard raw material lipid, the reaction temperature ranges from 250 to 300 DEG C, the reaction pressure ranges from 2 to 5 MPa and the reaction time is 8 to 30 minutes; (3) decoloring the crude diesel. The method solves the problem of glycerol excess in the production of the biodiesel with a short-chain alcohol as an ester-exchange reagent and also realizes the production possibility that the reaction yield is higher than 90% under the condition of a low ester-oil ratio; the obtained by-products can be directly used without being separated subsequently; the color of the prepare