NOVELTY - Method for producing biodiesel by extraction, ester exchange and separation coupling technology, involves (a) mixing oil-containing raw materials with low alcohol and solvent amidine or guanidine, (b) separating biodiesel and glycerol, (c) carrying out extraction and ester exchange process, (d) separating the raw material and reaction liquid by separating the filtered liquid into biodiesel phase and glycerol phase, (e) mixing glycerol phase and fatty acid or fatty acid ester to obtain diacylglycerol and monoglyceride, and (f) carrying out catalyst recycling process.    USE - The method is useful for producing biodiesel.    ADVANTAGE - The method is simple and environmentally-friendly as the method is performed in clean environment, enables easy recycling, and has less preparation process, mild reaction condition and good industrial prospect.    DETAILED DESCRIPTION - Method for producing biodiesel by extraction, ester exchange and separation coupling technology, involves (a) mixing oil-containing raw materials with low alcohol and solvent amidine or guanidine in a reactor, where the solvent amidine or guanidine is used both as extraction solvent and catalyst to perform the extraction and ester exchange steps simultaneously, (b) separating the biodiesel and glycerol by using the reversible convertible performance of the solvent, and performing reconversion and recycling process, (c) carrying out extraction and ester exchange process by mixing oil-containing raw materials with low alcohol and solvent amidine or guanidine in a certain ratio such that the molar ratio of oil and low alcohol is 1:50-1:350 and the mass of solvent amidine or guanidine is 5-85% of the total mass of raw material and performing reaction at 20-90 degrees C for 0.5-6 hours, (d) separating the raw material and reaction liquid by separating the filtered liquid as biodiesel phase and glycerol phase using reversible convertible performance of solvent such that both phases contain catalyst, allowing carbon dioxide to pass into the biodiesel phase at 20-80 degrees C for 2 minutes-2 hours and at a flow rate of 16-160 ml/minute, and separating the ion liquid and biodiesel, (e) mixing glycerol phase and fatty acid or fatty acid ester in a molar ratio of 1:1-1:6 to perform ester exchange reaction to obtain diacylglycerol and monoglyceride, maintaining the reaction temperature at 20-80 degrees C and reaction time for 0.5-6 hours, adding carbon dioxide for allowing conversion of catalyst and alcohol to ionic phase, and separating liquid from ester phase, and (f) carrying out catalyst recycling process, by adding nitrogen into the separated ion catalyst at flow rate of 16-160 ml/minute for 2 minutes-2 hours, displacing out carbon dioxide, weakening the polarity to nonionic state, and recycling the amidine or guanidine material.