The invention discloses a method for preparing lubricating oil base oil from chemically-modified catering waste oil, and belongs to the technical field of chemistry and chemical engineering. The method comprises the following steps of firstly performing an ester exchange reaction on pretreated catering waste oil and methanol under the effect of a catalyst to obtain fatty acid methyl esters, then performing an in-situ epoxidation reaction on the fatty acid methyl esters and formic acid in the presence of the catalyst to obtain epoxidized fatty acid methyl esters, and finally performing epoxy key ring cleavage reaction on the epoxidized fatty acid methyl esters and anhydride in the presence of the catalyst and under the protection of nitrogen gas so as to obtain triester derivative lubricating oil base oil. A new method of resource utilization of the catering waste oil is developed, a prepared triester derivative improves the low temperature fluidity and the thermal oxidation stability of the catering waste oil and is used as a replacement of traditional mineral based lubricating oil base oil, the purpose of turning waste into wealth is realized, the purposes of improving ecologicalenvironment and relieving energy resource crisis can be reached, and the method has high popularization and application value.