Abstract: By the combining application of the multiplication reaction between benzoyl peroxide (BPO) and potassium iodate in the presence of potassium iodide and of the 2 nd derivation in the photometric titration,the sensitivity of the conventional iodimetric determination of BPO in wheat flour was reported to be raised to about 200 times,and a detection limit of 0.1 mg·L-1 was acheved.In its application to the analysis of wheat flour samples,RSD′s obtained were in the range of 1.3%-2.8% and recoveries found were in the range from 98.6%-102.2%.Results obtained by the proposed method were found to be in consistency with those obtained by the GB standard method (GB/T 18415-2001).