Abstract: GC/MS method was adopted to rapidly determine diphenidol in the blood of dead patients sichened by poisoning, whose blood concentration was 13.28 mg L^－1. The retention time of diphenidol is 13.417 min and the mass fragment ions of diphenidol that can be seen in mass spectrum are m/z 127, m/z 98, and m/z 77. In addition, we also found benzophenone and benzhydrol, which are metabolites of diphenidol. The above data can provide useful information for relevant research of diphenidol.