The invention discloses a composition containing high-purity cefdinir and a preparation method of the composition. A cefdinir polymer contained in the composition is lower than 0.20 percent. The preparation method comprises the following steps: adopting the cefdinir prepared by the prior art as a starting material, dissolving, decoloring with active carbon, purifying with resin, acidifying and crystallizing to obtain the composition containing the high-purity cefdinir. The composition containing the high-purity cefdinir and the preparation method disclosed by the invention have the advantages that the content of the allergic cefdinir polymer is low, so that the risk of anaphylactic reaction of a patient is greatly reduced; and a preparation process is simple and convenient in operation and stable in technology and is suitable for industrial production.