The invention relates to the technical field of synthesis and processing of glyceride, and specifically relates to a preparation method of reducing iodine value of glyceride. The preparation method ofreducing iodine value of glyceride includes catalytic reaction of glyceride, saturated fatty acid and alkali under the action of lipase to prepare the glyceride with low iodine value; the iodine value of glyceride is effectively reduced by sufficient amount of saturated fatty acid residues provided by salts of saturated fatty acids that are produced by corresponding saturated fatty acid and alkali in-situ and by catalytic action of non-directed lipase to allow milder reaction conditions with less side reactions.